Provided by: postfix_2.2.10-1_i386 bug

NAME

       postconf - Postfix configuration parameters

SYNOPSIS

       postconf parameter ...

       postconf -e "parameter=value" ...

DESCRIPTION

       The  Postfix main.cf configuration file specifies a small subset of all
       the parameters that control the operation of the Postfix  mail  system.
       Parameters not specified in main.cf are left at their default values.

       The general format of the main.cf file is as follows:

       ·      Each  logical line has the form "parameter = value".  Whitespace
              around the "=" is ignored, as is whitespace  at  the  end  of  a
              logical line.

       ·      Empty  lines and whitespace-only lines are ignored, as are lines
              whose first non-whitespace character is a ‘#’.

       ·      A logical line starts with  non-whitespace  text.  A  line  that
              starts with whitespace continues a logical line.

       ·      A parameter value may refer to other parameters.

              ·      The  expressions  "$name",  "${name}"  or  "$(name)"  are
                     recursively replaced by the value of the named parameter.

              ·      The  expression  "${name?value}"  expands to "value" when
                     "$name" is non-empty. This form is supported with Postfix
                     version 2.2 and later.

              ·      The  expression  "${name:value}"  expands to "value" when
                     "$name" is empty. This form  is  supported  with  Postfix
                     version 2.2 and later.

       ·      When the same parameter is defined multiple times, only the last
              instance is remembered.

       ·      Otherwise, the order of main.cf parameter definitions  does  not
              matter.

       The  remainder  of  this  document  is  a  description  of  all Postfix
       configuration parameters. Default values are shown after the  parameter
       name  in  parentheses,  and  can  be  looked  up with the "postconf -d"
       command.

       Note:  this  is  not  an  invitation  to  make   changes   to   Postfix
       configuration  parameters. Unnecessary changes can impair the operation
       of the mail system.

2bounce_notice_recipient (default: postmaster)

       The recipient of undeliverable mail that  cannot  be  returned  to  the
       sender.  This feature is enabled with the notify_classes parameter.

access_map_reject_code (default: 554)

       The  numerical  Postfix  SMTP  server  response  code  when a client is
       rejected by an access(5) map restriction.

       Do not change this unless you have a complete understanding of RFC 821.

address_verify_default_transport (default: $default_transport)

       Overrides   the   default_transport   parameter   setting  for  address
       verification probes.

       This feature is available in Postfix 2.1 and later.

address_verify_local_transport (default: $local_transport)

       Overrides   the   local_transport   parameter   setting   for   address
       verification probes.

       This feature is available in Postfix 2.1 and later.

address_verify_map (default: empty)

       Optional  lookup  table  for  persistent  address  verification  status
       storage.  The table is maintained by  the  verify(8)  service,  and  is
       opened before the process releases privileges.

       By  default,  the  information  is kept in volatile memory, and is lost
       after "postfix reload" or "postfix stop".

       Specify a location in a file system that  will  not  fill  up.  If  the
       database  becomes  corrupted,  the  world  comes  to an end. To recover
       delete the file and do "postfix reload".

       Examples:

       address_verify_map = hash:/etc/postfix/verify
       address_verify_map = btree:/etc/postfix/verify

       This feature is available in Postfix 2.1 and later.

address_verify_negative_cache (default: yes)

       Enable caching of failed address verification probe results.  When this
       feature  is  enabled, the cache may pollute quickly with garbage.  When
       this feature is disabled, Postfix will generate an  address  probe  for
       every lookup.

       This feature is available in Postfix 2.1 and later.

address_verify_negative_expire_time (default: 3d)

       The   time  after  which  a  failed  probe  expires  from  the  address
       verification cache.

       Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.1 and later.

address_verify_negative_refresh_time (default: 3h)

       The time after which a failed address verification probe  needs  to  be
       refreshed.

       Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.1 and later.

address_verify_poll_count (default: 3)

       How  many times to query the verify(8) service for the completion of an
       address verification request in progress.

       The default poll count is 3.

       Specify 1 to implement a crude form of  greylisting,  that  is,  always
       defer the first delivery request for a never seen before address.

       Example:

       address_verify_poll_count = 1

       This feature is available in Postfix 2.1 and later.

address_verify_poll_delay (default: 3s)

       The delay between queries for the completion of an address verification
       request in progress.

       The default polling delay is 3 seconds.

       Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.1 and later.

address_verify_positive_expire_time (default: 31d)

       The time after which  a  successful  probe  expires  from  the  address
       verification cache.

       Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.1 and later.

address_verify_positive_refresh_time (default: 7d)

       The  time  after which a successful address verification probe needs to
       be refreshed.  The address verification status is not updated when  the
       probe fails (optimistic caching).

       Time units: s (seconds), m (minutes), h (hours), d (days), w (weeks).

       This feature is available in Postfix 2.1 and later.

address_verify_relay_transport (default: $relay_transport)

       Overrides   the   relay_transport   parameter   setting   for   address
       verification probes.

       This feature is available in Postfix 2.1 and later.

address_verify_relayhost (default: $relayhost)

       Overrides the relayhost  parameter  setting  for  address  verification
       probes.

       This feature is available in Postfix 2.1 and later.

address_verify_sender (default: postmaster)

       The  sender  address  to  use  in address verification probes. To avoid
       problems with address probes that  are  sent  in  response  to  address
       probes,  the Postfix SMTP server excludes the probe sender address from
       all SMTPD access blocks.

       Specify an empty value (address_verify_sender =) or <> if you  want  to
       use  the  null  sender address. Beware, some sites reject mail from <>,
       even though RFCs require that such addresses be accepted.

       Examples:

       address_verify_sender = <>
       address_verify_sender = postmaster@my.domain

       This feature is available in Postfix 2.1 and later.

address_verify_service_name (default: verify)

       The name of the verify(8) address verification  service.  This  service
       maintains  the  status  of sender and/or recipient address verification
       probes, and generates probes on request by other Postfix processes.

address_verify_transport_maps (default: $transport_maps)

       Overrides the transport_maps parameter setting for address verification
       probes.

       This feature is available in Postfix 2.1 and later.

address_verify_virtual_transport (default: $virtual_transport)

       Overrides   the   virtual_transport   parameter   setting  for  address
       verification probes.

       This feature is available in Postfix 2.1 and later.

alias_database (default: see postconf -d output)

       The alias  databases  for  local(8)  delivery  that  are  updated  with
       "newaliases" or with "sendmail -bi".

       This  is  a separate configuration parameter because not all the tables
       specified with $alias_maps have to be local files.

       Examples:

       alias_database = hash:/etc/aliases
       alias_database = hash:/etc/mail/aliases

alias_maps (default: see postconf -d output)

       The alias databases that are used for local(8) delivery. See aliases(5)
       for syntax details.

       The default list is system dependent.  On systems with NIS, the default
       is to search the local alias database, then the NIS alias database.

       If you change the alias  database,  run  "postalias  /etc/aliases"  (or
       wherever  your  system  stores  the  mail  alias  file),  or simply run
       "newaliases" to build the necessary DBM or DB file.

       The local(8) delivery agent disallows regular  expression  substitution
       of $1 etc. in alias_maps, because that would open a security hole.

       The  local(8)  delivery  agent will silently ignore requests to use the
       proxymap(8) server within alias_maps. Instead it will  open  the  table
       directly.  Before Postfix version 2.2, the local(8) delivery agent will
       terminate with a fatal error.

       Examples:

       alias_maps = hash:/etc/aliases, nis:mail.aliases
       alias_maps = hash:/etc/aliases

allow_mail_to_commands (default: alias, forward)

       Restrict local(8) mail delivery to external commands.  The  default  is
       to  disallow delivery to "|command" in :include:  files (see aliases(5)
       for the text that defines this terminology).

       Specify zero or more of: alias, forward or include, in order  to  allow
       commands   in  aliases(5),  .forward  files  or  in  :include:   files,
       respectively.

       Example:

       allow_mail_to_commands = alias,forward,include

allow_mail_to_files (default: alias, forward)

       Restrict local(8) mail delivery to external files. The  default  is  to
       disallow  "/file/name" destinations in :include:  files (see aliases(5)
       for the text that defines this terminology).

       Specify zero or more of: alias, forward or include, in order  to  allow
       "/file/name"   destinations   in  aliases(5),  .forward  files  and  in
       :include:  files, respectively.

       Example:

       allow_mail_to_files = alias,forward,include

allow_min_user (default: no)

       Allow a recipient address to have  ‘-’  as  the  first  character.   By
       default,  this  is  not  allowed, to avoid accidents with software that
       passes email addresses via the command line. Such software would not be
       able  to  distinguish a malicious address from a bona fide command-line
       option. Although this can be  prevented  by  inserting  a  "--"  option
       terminator  into  the  command  line,  this  is  difficult  to  enforce
       consistently and globally.

allow_percent_hack (default: yes)

       Enable the rewriting of the form "user%domain" to "user@domain".   This
       is enabled by default.

       Note:  with  Postfix  version  2.2,  message  header  address rewriting
       happens only when one of the following conditions is true:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The message is received  from  a  network  client  that  matches
              $local_header_rewrite_clients,

       ·      The   message   is   received   from   the   network,   and  the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To     get     the     behavior    before    Postfix    2.2,    specify
       "local_header_rewrite_clients = static:all".

       Example:

       allow_percent_hack = no

allow_untrusted_routing (default: no)

       Forward mail with sender-specified  routing  (user[@%!]remote[@%!]site)
       from untrusted clients to destinations matching $relay_domains.

       By default, this feature is turned off.  This closes a nasty open relay
       loophole where a backup MX host can be  tricked  into  forwarding  junk
       mail to a primary MX host which then spams it out to the world.

       This  parameter  also  controls  if  non-local  addresses  with sender-
       specified routing can match Postfix access  tables.  By  default,  such
       addresses  cannot  match  Postfix access tables, because the address is
       ambiguous.

alternate_config_directories (default: empty)

       A list of non-default Postfix configuration  directories  that  may  be
       specified  with  "-c  config_directory" on the command line, or via the
       MAIL_CONFIG environment parameter.

       This list must  be  specified  in  the  default  Postfix  configuration
       directory, and is used by set-gid Postfix commands such as postqueue(1)
       and postdrop(1).

always_bcc (default: empty)

       Optional address that receives a "blind carbon copy"  of  each  message
       that is received by the Postfix mail system.

       Note:  if  mail  to  the BCC address bounces it will be returned to the
       sender.

       Note: automatic BCC recipients are produced  only  for  new  mail.   To
       avoid mailer loops, automatic BCC recipients are not generated for mail
       that Postfix forwards internally, nor for mail that  Postfix  generates
       itself.

anvil_rate_time_unit (default: 60s)

       The  time  unit  over which client connection rates and other rates are
       calculated.

       This feature is implemented by the anvil(8) service which is  not  part
       of the stable Postfix 2.1 release.

       The default interval is relatively short. Because of the high frequency
       of updates, the  anvil(8)  server  uses  volatile  memory  only.  Thus,
       information is lost whenever the process terminates.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

anvil_status_update_time (default: 600s)

       How frequently the anvil(8) connection and rate  limiting  server  logs
       peak usage information.

       This feature is available in Postfix 2.2 and later.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

append_at_myorigin (default: yes)

       With locally submitted mail, append the  string  "@$myorigin"  to  mail
       addresses  without  domain  information.  With remotely submitted mail,
       append the string "@$remote_header_rewrite_domain" instead.

       Note 1: this feature is enabled by default and must not be turned  off.
       Postfix does not support domain-less addresses.

       Note  2:  with  Postfix  version  2.2, message header address rewriting
       happens only when one of the following conditions is true:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The message is received  from  a  network  client  that  matches
              $local_header_rewrite_clients,

       ·      The   message   is   received   from   the   network,   and  the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To     get     the     behavior    before    Postfix    2.2,    specify
       "local_header_rewrite_clients = static:all".

append_dot_mydomain (default: yes)

       With  locally  submitted  mail,  append  the  string  ".$mydomain"   to
       addresses  that  have no ".domain" information. With remotely submitted
       mail, append the string ".$remote_header_rewrite_domain" instead.

       Note 1: this feature is enabled by default. If disabled, users will not
       be  able  to  send  mail  to  "user@partialdomainname" but will have to
       specify full domain names instead.

       Note 2: with Postfix version  2.2,  message  header  address  rewriting
       happens only when one of the following conditions is true:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The  message  is  received  from  a  network client that matches
              $local_header_rewrite_clients,

       ·      The  message   is   received   from   the   network,   and   the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To    get    the    behavior    before     Postfix     2.2,     specify
       "local_header_rewrite_clients = static:all".

application_event_drain_time (default: 100s)

       How  long  the  postkick(1)  command  waits  for a request to enter the
       server’s input buffer before giving up.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

       This feature is available in Postfix 2.1 and later.

authorized_flush_users (default: static:anyone)

       List of users who are authorized to flush the queue.

       By default, all users are allowed to flush the queue.  Access is always
       granted if the invoking user is the super-user or the $mail_owner user.
       Otherwise,  the  real  UID  of  the  process is looked up in the system
       password file, and access is granted only if  the  corresponding  login
       name  is  on  the  access  list.   The  username  "unknown" is used for
       processes whose real UID is not found in the password file.

       Specify a list of user names, "/file/name"  or  "type:table"  patterns,
       separated  by  commas  and/or  whitespace.  The list is matched left to
       right, and the search stops on the  first  match.  Specify  "!name"  to
       exclude a name from the list. A "/file/name" pattern is replaced by its
       contents; a "type:table" lookup table is matched when a name matches  a
       lookup  key  (the  lookup  result  is ignored).  Continue long lines by
       starting the next line with whitespace.

       This feature is available in Postfix 2.2 and later.

authorized_mailq_users (default: static:anyone)

       List of users who are authorized to view the queue.

       By default, all users are allowed to view the queue.  Access is  always
       granted if the invoking user is the super-user or the $mail_owner user.
       Otherwise, the real UID of the process  is  looked  up  in  the  system
       password  file,  and  access is granted only if the corresponding login
       name is on the  access  list.   The  username  "unknown"  is  used  for
       processes whose real UID is not found in the password file.

       Specify  a  list  of user names, "/file/name" or "type:table" patterns,
       separated by commas and/or whitespace. The  list  is  matched  left  to
       right,  and  the  search  stops  on the first match. Specify "!name" to
       exclude a name from the list. A "/file/name" pattern is replaced by its
       contents;  a "type:table" lookup table is matched when a name matches a
       lookup key (the lookup result is  ignored).   Continue  long  lines  by
       starting the next line with whitespace.

       This feature is available in Postfix 2.2 and later.

authorized_submit_users (default: static:anyone)

       List  of  users  who are authorized to submit mail with the sendmail(1)
       command (and with the privileged postdrop(1) helper command).

       By default, all users are allowed to submit mail.  Otherwise, the  real
       UID of the process is looked up in the system password file, and access
       is granted only if the corresponding login name is on the access  list.
       The  username  "unknown"  is  used  for processes whose real UID is not
       found in the password file. To deny mail submission access to all users
       specify an empty list.

       Specify  a  list  of user names, "/file/name" or "type:table" patterns,
       separated by commas and/or whitespace. The  list  is  matched  left  to
       right,  and  the  search  stops  on the first match. Specify "!name" to
       exclude a name from the list. A "/file/name" pattern is replaced by its
       contents;  a "type:table" lookup table is matched when a name matches a
       lookup key (the lookup result is  ignored).   Continue  long  lines  by
       starting the next line with whitespace.

       This feature is available in Postfix 2.2 and later.

authorized_verp_clients (default: $mynetworks)

       What  SMTP  clients  are  allowed  to  specify the XVERP command.  This
       command requests that mail be delivered one recipient at a time with  a
       per recipient return address.

       By default, only trusted clients are allowed to specify XVERP.

       This  parameter  was  introduced  with  Postfix  version  1.1.  Postfix
       version 2.1 renamed this parameter to smtpd_authorized_verp_clients and
       changed the default to none.

       Specify  a list of network/netmask patterns, separated by commas and/or
       whitespace. The mask specifies the number of bits in the  network  part
       of a host address. You can also specify hostnames or .domain names (the
       initial  dot  causes  the  domain  to  match  any   name   below   it),
       "/file/name"  or  "type:table"  patterns.   A  "/file/name"  pattern is
       replaced by its contents; a "type:table" lookup table is matched when a
       table  entry  matches  a  lookup string (the lookup result is ignored).
       Continue long lines by starting the next line with whitespace.

       Note: IP version 6 address information must be specified inside  []  in
       the   authorized_verp_clients   value,  and  in  files  specified  with
       "/file/name".  IP version 6 addresses contain the  ":"  character,  and
       would otherwise be confused with a "type:table" pattern.

backwards_bounce_logfile_compatibility (default: yes)

       Produce  additional  bounce(8)  logfile  records  that  can  be read by
       Postfix versions before 2.0. The current and more  extensible  "name  =
       value"  format  is  needed  in  order  to  implement more sophisticated
       functionality.

       This feature is available in Postfix 2.1 and later.

berkeley_db_create_buffer_size (default: 16777216)

       The per-table I/O buffer size for programs that create Berkeley DB hash
       or btree tables.  Specify a byte count.

       This feature is available in Postfix 2.0 and later.

berkeley_db_read_buffer_size (default: 131072)

       The  per-table  I/O buffer size for programs that read Berkeley DB hash
       or btree tables.  Specify a byte count.

       This feature is available in Postfix 2.0 and later.

best_mx_transport (default: empty)

       Where the Postfix SMTP client should deliver mail  when  it  detects  a
       "mail  loops  back  to  myself"  error condition. This happens when the
       local MTA is the best SMTP mail exchanger for a destination not  listed
       in       $mydestination,      $inet_interfaces,      $proxy_interfaces,
       $virtual_alias_domains, or $virtual_mailbox_domains.  By  default,  the
       Postfix SMTP client returns such mail as undeliverable.

       Specify, for example, "best_mx_transport = local" to pass the mail from
       the SMTP client to the local(8) delivery agent.  You  can  specify  any
       message  delivery "transport" or "transport:nexthop" that is defined in
       the master.cf file. See the transport(5) manual page for the syntax and
       meaning of "transport" or "transport:nexthop".

       However,  this  feature  is expensive because it ties up a Postfix SMTP
       client process while the local(8) delivery agent is doing its work.  It
       is  more  efficient (for Postfix) to list all hosted domains in a table
       or database.

biff (default: yes)

       Whether or not to use the local biff service.  This service sends  "new
       mail"  notifications  to users who have requested new mail notification
       with the UNIX command "biff y".

       For compatibility reasons this feature is on by  default.   On  systems
       with  lots  of interactive users, the biff service can be a performance
       drain.  Specify "biff = no" in main.cf to disable.

body_checks (default: empty)

       Optional lookup tables for  content  inspection  as  specified  in  the
       body_checks(5) manual page.

       Note: with Postfix versions before 2.0, these rules inspect all content
       after the primary message headers.

body_checks_size_limit (default: 51200)

       How much text in a message body segment (or attachment, if  you  prefer
       to  use  that term) is subjected to body_checks inspection.  The amount
       of text is limited to avoid scanning huge attachments.

       This feature is available in Postfix 2.0 and later.

bounce_notice_recipient (default: postmaster)

       The recipient of postmaster notifications with the message  headers  of
       mail  that Postfix did not deliver and of SMTP conversation transcripts
       of mail that Postfix did not receive.  This feature is enabled with the
       notify_classes parameter.

bounce_queue_lifetime (default: 5d)

       The  maximal  time  a  bounce message is queued before it is considered
       undeliverable.  By default, this is the same as the queue life time for
       regular mail.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is d (days).

       Specify 0 when mail delivery should be tried only once.

       This feature is available in Postfix 2.1 and later.

bounce_service_name (default: bounce)

       The name of the bounce(8) service. This service maintains a  record  of
       failed delivery attempts and generates non-delivery notifications.

       This feature is available in Postfix 2.0 and later.

bounce_size_limit (default: 50000)

       The  maximal  amount  of  original  message text that is sent in a non-
       delivery notification. Specify a  byte  count.  If  you  increase  this
       limit,   then   you   should   increase  the  mime_nesting_limit  value
       proportionally.

broken_sasl_auth_clients (default: no)

       Enable inter-operability with SMTP clients that implement  an  obsolete
       version  of  the  AUTH command (RFC 2554). Examples of such clients are
       MicroSoft Outlook Express version 4 and MicroSoft Exchange version 5.0.

       Specify "broken_sasl_auth_clients = yes" to have Postfix advertise AUTH
       support in a non-standard way.

canonical_classes (default: envelope_sender, envelope_recipient,

       header_sender, header_recipient)
       What  addresses  are  subject  to  canonical_maps  address mapping.  By
       default, canonical_maps address mapping is applied to  envelope  sender
       and  recipient  addresses,  and  to  header sender and header recipient
       addresses.

       Specify  one   or   more   of:   envelope_sender,   envelope_recipient,
       header_sender, header_recipient

       This feature is available in Postfix 2.2 and later.

canonical_maps (default: empty)

       Optional   address  mapping  lookup  tables  for  message  headers  and
       envelopes.  The  mapping  is  applied  to  both  sender  and  recipient
       addresses,  in  both  envelopes  and in headers, as controlled with the
       canonical_classes parameter. This is typically used to clean  up  dirty
       addresses  from  legacy  mail  systems,  or  to  replace login names by
       Firstname.Lastname.  The table format and  lookups  are  documented  in
       canonical(5).  For an overview of Postfix address manipulations see the
       ADDRESS_REWRITING_README document.

       If you use this feature, run "postmap /etc/postfix/canonical" to  build
       the  necessary  DBM  or  DB  file  after every change. The changes will
       become visible after a minute or so.  Use "postfix reload" to eliminate
       the delay.

       Note:  with Postfix version 2.2, message header address mapping happens
       only when message header address rewriting is enabled:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The message is received  from  a  network  client  that  matches
              $local_header_rewrite_clients,

       ·      The   message   is   received   from   the   network,   and  the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To     get     the     behavior    before    Postfix    2.2,    specify
       "local_header_rewrite_clients = static:all".

       Examples:

       canonical_maps = dbm:/etc/postfix/canonical
       canonical_maps = hash:/etc/postfix/canonical

cleanup_service_name (default: cleanup)

       The name of the cleanup(8) service.  This  service  rewrites  addresses
       into  the  standard form, and performs canonical(5) address mapping and
       virtual(5) aliasing.

       This feature is available in Postfix 2.0 and later.

command_directory (default: see postconf -d output)

       The location of all postfix administrative commands.

command_execution_directory (default: empty)

       The local(8) delivery agent working directory for delivery to  external
       command.   Failure  to  change  directory  causes  the  delivery  to be
       deferred.

       The following $name expansions are done on  command_execution_directory
       before  the  directory  is changed. Expansion happens in the context of
       the delivery request.  The result of $name expansion is  filtered  with
       the     character     set     that     is     specified     with    the
       execution_directory_expansion_filter parameter.

       $user  The recipient’s username.

       $shell The recipient’s login shell pathname.

       $home  The recipient’s home directory.

       $recipient
              The full recipient address.

       $extension
              The optional recipient address extension.

       $domain
              The recipient domain.

       $local The entire recipient localpart.

       $recipient_delimiter
              The system-wide recipient address extension delimiter.

       ${name?value}
              Expands to value when $name is non-empty.

       ${name:value}
              Expands to value when $name is empty.

       Instead of $name you can also specify ${name} or $(name).

       This feature is available in Postfix 2.2 and later.

command_expansion_filter (default: see postconf -d output)

       Restrict the characters that the  local(8)  delivery  agent  allows  in
       $name  expansions  of $mailbox_command.  Characters outside the allowed
       set are replaced by underscores.

command_time_limit (default: 1000s)

       Time limit for delivery to external commands. This limit is used by the
       local(8)  delivery agent, and is the default time limit for delivery by
       the pipe(8) delivery agent.

       Note: if you set this time limit to a large value you must  update  the
       global ipc_timeout parameter as well.

config_directory (default: see postconf -d output)

       The default location of the Postfix main.cf and master.cf configuration
       files. This can be overruled via the following mechanisms:

       ·      The  MAIL_CONFIG  environment  variable  (daemon  processes  and
              commands).

       ·      The "-c" command-line option (commands only).

       With   Postfix   command   that   run   with   set-gid   privileges,  a
       config_directory  override  requires  either  root  privileges,  or  it
       requires     that     the     directory     is    listed    with    the
       alternate_config_directories parameter in the default main.cf file.

connection_cache_service (default: scache)

       The name of the  scache(8)  connection  cache  service.   This  service
       maintains a limited pool of cached sessions.

connection_cache_status_update_time (default: 600s)

       How   frequently  the  scache(8)  server  logs  usage  statistics  with
       connection cache hit and miss rates for logical  destinations  and  for
       physical endpoints.

connection_cache_ttl_limit (default: 2s)

       The  maximal  time-to-live  value  that  the scache(8) connection cache
       server allows. Requests that specify a larger TTL will be  stored  with
       the  maximum  allowed TTL. The purpose of this additional control is to
       protect the infrastructure against careless people. The  cache  TTL  is
       already bounded by $max_idle.

content_filter (default: empty)

       The  name  of  a  mail delivery transport that filters mail after it is
       queued.

       This parameter uses the same syntax as the right-hand side of a Postfix
       transport(5)  table. This setting has a lower precedence than a content
       filter  that  is  specified  with  an   access(5)   table   or   in   a
       header_checks(5) or body_checks(5) table.

daemon_directory (default: see postconf -d output)

       The directory with Postfix support programs and daemon programs.  These
       should not be invoked directly by humans. The directory must  be  owned
       by root.

daemon_timeout (default: 18000s)

       How  much  time  a  Postfix daemon process may take to handle a request
       before it is terminated by a built-in watchdog timer.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

debug_peer_level (default: 2)

       The  increment  in verbose logging level when a remote client or server
       matches a pattern in the debug_peer_list parameter.

debug_peer_list (default: empty)

       Optional list of remote client or server hostname  or  network  address
       patterns that cause the verbose logging level to increase by the amount
       specified in $debug_peer_level.

       Specify domain names, network/netmask patterns,  "/file/name"  patterns
       or   "type:table"  lookup  tables.  The  right-hand  side  result  from
       "type:table" lookups is ignored.

       Pattern   matching   of   domain   names   is   controlled    by    the
       parent_domain_matches_subdomains parameter.

       Examples:

       debug_peer_list = 127.0.0.1
       debug_peer_list = some.domain

debugger_command (default: empty)

       The  external  command  to  execute  when  a  Postfix daemon program is
       invoked with the -D option.

       Use "command .. & sleep 5" so that the debugger can attach  before  the
       process  marches  on. If you use an X-based debugger, be sure to set up
       your XAUTHORITY environment variable before starting Postfix.

       Example:

       debugger_command =
           PATH=/usr/bin:/usr/X11R6/bin
           xxgdb $daemon_directory/$process_name $process_id & sleep 5

default_database_type (default: see postconf -d output)

       The default database type for use in  newaliases(1),  postalias(1)  and
       postmap(1)  commands.  On  many UNIX systems the default type is either
       dbm or hash. The default setting is frozen when the Postfix  system  is
       built.

       Examples:

       default_database_type = hash
       default_database_type = dbm

default_delivery_slot_cost (default: 5)

       How  often  the Postfix queue manager’s scheduler is allowed to preempt
       delivery of one message with another.

       Each transport maintains a so-called "available delivery slot  counter"
       for  each message. One message can be preempted by another one when the
       other message can be delivered using  no  more  delivery  slots  (i.e.,
       invocations  of  delivery  agents) than the current message counter has
       accumulated (or will eventually  accumulate  -  see  about  slot  loans
       below).  This parameter controls how often is the counter incremented -
       it happens after each default_delivery_slot_cost recipients  have  been
       delivered.

       The  cost of 0 is used to disable the preempting scheduling completely.
       The minimum value the scheduling algorithm can use is 2 - use it if you
       want  to  maximize  the  message  throughput rate. Although there is no
       maximum, it doesn’t make much sense to use values above say 50.

       The only reason why the value of 2 is not the default is the  way  this
       parameter affects the delivery of mailing-list mail. In the worst case,
       their  delivery  can   take   somewhere   between   (cost+1/cost)   and
       (cost/cost-1) times more than if the preemptive scheduler was disabled.
       The default value of 5 turns out to provide reasonable message response
       times while making sure the mailing-list deliveries are not extended by
       more than 20-25 percent even in the worst case.

       Examples:

       default_delivery_slot_cost = 0
       default_delivery_slot_cost = 2

default_delivery_slot_discount (default: 50)

       The  default  value  for   transport-specific   _delivery_slot_discount
       settings.

       This  parameter  speeds  up  the  moment  when a message preemption can
       happen. Instead of waiting until the  full  amount  of  delivery  slots
       required    is    available,    the    preemption   can   happen   when
       transport_delivery_slot_discount percent of the  required  amount  plus
       transport_delivery_slot_loan  still  remains  to  be accumulated.  Note
       that the full amount will still have to be accumulated  before  another
       preemption can take place later.

default_delivery_slot_loan (default: 3)

       The  default value for transport-specific _delivery_slot_loan settings.

       This parameter speeds up the  moment  when  a  message  preemption  can
       happen.  Instead  of  waiting  until  the full amount of delivery slots
       required   is   available,   the    preemption    can    happen    when
       transport_delivery_slot_discount  percent  of  the required amount plus
       transport_delivery_slot_loan still remains  to  be  accumulated.   Note
       that  the  full amount will still have to be accumulated before another
       preemption can take place later.

default_destination_concurrency_limit (default: 20)

       The  default  maximal  number  of  parallel  deliveries  to  the   same
       destination.   This  is the default limit for delivery via the lmtp(8),
       pipe(8), smtp(8) and virtual(8) delivery agents.

default_destination_recipient_limit (default: 50)

       The default maximal number of recipients per message delivery.  This is
       the  default  limit  for delivery via the lmtp(8), pipe(8), smtp(8) and
       virtual(8) delivery agents.

       Setting this parameter to a value of  1  changes  the  meaning  of  the
       corresponding  per-destination  concurrency  limit from concurrency per
       domain into concurrency per recipient.

default_extra_recipient_limit (default: 1000)

       The default value for the extra  per-transport  limit  imposed  on  the
       number of in-memory recipients.  This extra recipient space is reserved
       for the cases when the Postfix queue manager’s scheduler  preempts  one
       message with another and suddenly needs some extra recipients slots for
       the chosen message in order to avoid performance degradation.

default_minimum_delivery_slots (default: 3)

       How many recipients a message must have in order to invoke the  Postfix
       queue  manager’s  scheduling  algorithm  at  all.  Messages which would
       never accumulate at least this many delivery  slots  (subject  to  slot
       cost parameter as well) are never preempted.

default_privs (default: nobody)

       The  default rights used by the local(8) delivery agent for delivery to
       external file or command.  These  rights  are  used  when  delivery  is
       requested  from  an  aliases(5)  file  that  is  owned by root, or when
       delivery is done on behalf of root. DO NOT SPECIFY A PRIVILEGED USER OR
       THE POSTFIX OWNER.

default_process_limit (default: 100)

       The  default  maximal  number of Postfix child processes that provide a
       given service. This limit can be overruled for specific services in the
       master.cf file.

default_rbl_reply (default: see postconf -d output)

       The  default  SMTP  server  response  template  for  a  request that is
       rejected by an RBL-based restriction. This template can be overruled by
       specific entries in the optional rbl_reply_maps lookup table.

       This feature is available in Postfix 2.0 and later.

       The template is subject to exactly one level of $name substitution:

       $client
              The  client hostname and IP address, formatted as name[address].

       $client_address
              The client IP address.

       $client_name
              The client hostname or "unknown".

       $helo_name
              The hostname given in HELO or EHLO command or empty string.

       $rbl_class
              The blacklisted entity type: Client host, Helo  command,  Sender
              address, or Recipient address.

       $rbl_code
              The   numerical  SMTP  response  code,  as  specified  with  the
              maps_rbl_reject_code configuration parameter.

       $rbl_domain
              The RBL domain where $rbl_what is blacklisted.

       $rbl_reason
              The reason why $rbl_what is blacklisted, or an empty string.

       $rbl_what
              The entity that is blacklisted (an IP  address,  a  hostname,  a
              domain  name, or an email address whose domain was blacklisted).

       $recipient
              The recipient address or <> in case of the null address.

       $recipient_domain
              The recipient domain or empty string.

       $recipient_name
              The recipient address localpart or <> in case of null address.

       $sender
              The sender address or <> in case of the null address.

       $sender_domain
              The sender domain or empty string.

       $sender_name
              The sender address localpart or <> in case of the null  address.

       ${name?text}
              Expands to ‘text’ if $name is not empty.

       ${name:text}
              Expands to ‘text’ if $name is empty.

       Instead of $name you can also specify ${name} or $(name).

default_recipient_limit (default: 10000)

       The  default  per-transport  upper  limit  on  the  number of in-memory
       recipients.    These   limits   take   priority   over    the    global
       qmgr_message_recipient_limit after the message has been assigned to the
       respective  transports.   See  also  default_extra_recipient_limit  and
       qmgr_message_recipient_minimum.

default_transport (default: smtp)

       The  default  mail  delivery  transport  for  domains that do not match
       $mydestination,          $inet_interfaces,           $proxy_interfaces,
       $virtual_alias_domains,  $virtual_mailbox_domains,  or  $relay_domains.
       This information can be overruled with the transport(5) table.

       Specify a string of the form transport:nexthop, where transport is  the
       name  of  a mail delivery transport defined in master.cf.  The :nexthop
       part is optional.  For more details see the transport(5) manual page.

       Example:

       default_transport = uucp:relayhostname

default_verp_delimiters (default: +=)

       The two default VERP delimiter  characters.  These  are  used  when  no
       explicit  delimiters  are specified with the SMTP XVERP command or with
       the "sendmail -V" command-line  option.  Specify  characters  that  are
       allowed by the verp_delimiter_filter setting.

       This feature is available in Postfix 1.1 and later.

defer_code (default: 450)

       The  numerical  Postfix  SMTP  server  response code when a remote SMTP
       client request is rejected by the "defer" restriction.

       Do not change this unless you have a complete understanding of RFC 821.

defer_service_name (default: defer)

       The  name  of  the defer(8) service. This service maintains a record of
       failed delivery attempts and generates non-delivery notifications.

       This feature is available in Postfix 2.0 and later.

defer_transports (default: empty)

       The names of message delivery transports that should not  be  delivered
       to  unless  someone issues "sendmail -q" or equivalent. Specify zero or
       more names of mail delivery transports names that appear in  the  first
       field of master.cf.

       Example:

       defer_transports = smtp

delay_notice_recipient (default: postmaster)

       The  recipient  of postmaster notifications with the message headers of
       mail that cannot be delivered within $delay_warning_time time units.

       This feature is enabled with the delay_warning_time parameter.

delay_warning_time (default: 0h)

       The time after which the sender receives the message  headers  of  mail
       that is still queued.

       To enable this feature, specify a non-zero integral value.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is h (hours).

deliver_lock_attempts (default: 20)

       The maximal number of attempts  to  acquire  an  exclusive  lock  on  a
       mailbox file or bounce(8) logfile.

deliver_lock_delay (default: 1s)

       The  time  between  attempts  to acquire an exclusive lock on a mailbox
       file or bounce(8) logfile.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

disable_dns_lookups (default: no)

       Disable  DNS  lookups  in  the  Postfix  SMTP  and  LMTP  clients. When
       disabled, hosts are looked up with the gethostbyname()  system  library
       routine which normally also looks in /etc/hosts.

       DNS lookups are enabled by default.

disable_mime_input_processing (default: no)

       Turn  off  MIME  processing  while  receiving  mail. This means that no
       special treatment is given to Content-Type: message headers,  and  that
       all  text after the initial message headers is considered to be part of
       the message body.

       This feature is available in Postfix 2.0 and later.

       Mime input processing is enabled by default, and is needed in order  to
       recognize MIME headers in message content.

disable_mime_output_conversion (default: no)

       Disable  the conversion of 8BITMIME format to 7BIT format.  Mime output
       conversion is needed when the destination does not  advertise  8BITMIME
       support.

       This feature is available in Postfix 2.0 and later.

disable_verp_bounces (default: no)

       Disable sending one bounce report per recipient.

       The default, one per recipient, is what ezmlm needs.

       This feature is available in Postfix 1.1 and later.

disable_vrfy_command (default: no)

       Disable  the  SMTP  VRFY  command.  This  stops some techniques used to
       harvest email addresses.

       Example:

       disable_vrfy_command = no

dont_remove (default: 0)

       Don’t remove queue files and save them to the "saved" mail queue.  This
       is a debugging aid.  To inspect the envelope information and content of
       a Postfix queue file, use the postcat(1) command.

double_bounce_sender (default: double-bounce)

       The sender address of postmaster notifications that  are  generated  by
       the  mail  system.  All  mail to this address is silently discarded, in
       order to terminate mail bounce loops.

duplicate_filter_limit (default: 1000)

       The maximal number of addresses remembered  by  the  address  duplicate
       filter  for  aliases(5)  or virtual(5) alias expansion, or for showq(8)
       queue displays.

empty_address_recipient (default: MAILER-DAEMON)

       The recipient of mail addressed to the null address.  Postfix does  not
       accept  such  addresses in SMTP commands, but they may still be created
       locally as the result of configuration or software error.

enable_errors_to (default: no)

       Report mail delivery errors to the  address  specified  with  the  non-
       standard  Errors-To:  message  header,  instead  of the envelope sender
       address (this feature is removed with Postfix 2.2,  is  turned  off  by
       default  with  Postfix  2.1, and is always turned on with older Postfix
       versions).

enable_original_recipient (default: yes)

       Enable support for the X-Original-To message  header.  This  header  is
       needed for multi-recipient mailboxes.

       When  this  parameter  is  set  to  yes, the cleanup(8) daemon performs
       duplicate  elimination  on  distinct  pairs  of  (original   recipient,
       rewritten  recipient), and generates non-empty original recipient queue
       file records.

       When this parameter is  set  to  no,  the  cleanup(8)  daemon  performs
       duplicate  elimination  on  the  rewritten  recipient address only, and
       generates empty original recipient queue file records.

       This feature is available in Postfix 2.1 and later. With  Postfix  2.0,
       support  for  the  X-Original-To  message  header  is always turned on.
       Postfix versions before 2.0  have  no  support  for  the  X-Original-To
       message header.

error_notice_recipient (default: postmaster)

       The  recipient of postmaster notifications about mail delivery problems
       that are caused by  policy,  resource,  software  or  protocol  errors.
       These notifications are enabled with the notify_classes parameter.

error_service_name (default: error)

       The  name  of  the  error(8) pseudo delivery agent. This service always
       returns mail as undeliverable.

       This feature is available in Postfix 2.0 and later.

execution_directory_expansion_filter (default: see postconf -d output)

       Restrict the characters that the  local(8)  delivery  agent  allows  in
       $name  expansions  of $command_execution_directory.  Characters outside
       the allowed set are replaced by underscores.

       This feature is available in Postfix 2.2 and later.

expand_owner_alias (default: no)

       When delivering to an alias "aliasname" that has  an  "owner-aliasname"
       companion  alias,  set  the envelope sender address to the expansion of
       the "owner-aliasname" alias. Normally, Postfix sets the envelope sender
       address to the name of the "owner-aliasname" alias.

export_environment (default: see postconf -d output)

       The list of environment variables that a Postfix process will export to
       non-Postfix processes. The TZ variable is needed for sane time  keeping
       on System-V-ish systems.

       Specify   a  list  of  names  and/or  name=value  pairs,  separated  by
       whitespace or comma. The name=value form is supported with Postfix  2.1
       and later.

       Example:

       export_environment = TZ PATH=/bin:/usr/bin

extract_recipient_limit (default: 10240)

       The  maximal  number  of  recipient addresses that Postfix will extract
       from message headers when mail is submitted with "sendmail -t".

       This feature was removed in Postfix 2.1.

fallback_relay (default: empty)

       Optional list of relay hosts for SMTP destinations that can’t be  found
       or that are unreachable.

       By  default,  mail  is returned to the sender when a destination is not
       found, and delivery is deferred if a destination is unreachable.

       The fallback relays must be SMTP destinations. Specify a domain,  host,
       host:port,  [host]:port,  [address]  or [address]:port; the form [host]
       turns off MX lookups.   If  you  specify  multiple  SMTP  destinations,
       Postfix will try them in the specified order.

       Note:  do  not  use the fallback_relay feature when relaying mail for a
       backup or primary MX domain. Mail would loop  between  the  Postfix  MX
       host  and  the  fallback_relay  host  when  the  final  destination  is
       unavailable.

       ·      In main.cf specify "relay_transport = relay",

       ·      In master.cf specify "-o fallback_relay =" (i.e., empty) at  the
              end of the relay entry.

       ·      In transport maps, specify "relay:nexthop..."  as the right-hand
              side for backup or primary MX domain entries.

       These are default settings in Postfix version 2.2 and later.

fallback_transport (default: empty)

       Optional message delivery transport that the  local(8)  delivery  agent
       should  use  for names that are not found in the aliases(5) database or
       in the UNIX passwd database.

fast_flush_domains (default: $relay_domains)

       Optional list of destinations that  are  eligible  for  per-destination
       logfiles with mail that is queued to those destinations.

       By   default,   Postfix   maintains  "fast  flush"  logfiles  only  for
       destinations that the Postfix SMTP server is willing to relay to  (i.e.
       the   default   is:  "fast_flush_domains  =  $relay_domains";  see  the
       relay_domains parameter in the postconf(5) manual).

       Specify  a  list  of  hosts  or  domains,  "/file/name"   patterns   or
       "type:table"  lookup  tables,  separated  by  commas and/or whitespace.
       Continue long lines by  starting  the  next  line  with  whitespace.  A
       "/file/name" pattern is replaced by its contents; a "type:table" lookup
       table is matched when the domain or its parent domain appears as lookup
       key.

       Specify  "fast_flush_domains  ="  (i.e.,  empty) to disable the feature
       altogether.

fast_flush_purge_time (default: 7d)

       The time after which an empty per-destination "fast flush"  logfile  is
       deleted.

       You  can  specify  the  time  as a number, or as a number followed by a
       letter that indicates the time  unit:  s=seconds,  m=minutes,  h=hours,
       d=days, w=weeks.  The default time unit is days.

fast_flush_refresh_time (default: 12h)

       The  time  after  which  a  non-empty  but unread per-destination "fast
       flush" logfile needs to be refreshed.  The contents of  a  logfile  are
       refreshed by requesting delivery of all messages listed in the logfile.

       You can specify the time as a number, or as  a  number  followed  by  a
       letter  that  indicates  the  time unit: s=seconds, m=minutes, h=hours,
       d=days, w=weeks.  The default time unit is hours.

fault_injection_code (default: 0)

       Force specific internal tests to fail, to test the handling  of  errors
       that are difficult to reproduce otherwise.

flush_service_name (default: flush)

       The   name  of  the  flush(8)  service.  This  service  maintains  per-
       destination logfiles with the queue file names of mail that  is  queued
       for those destinations.

       This feature is available in Postfix 2.0 and later.

fork_attempts (default: 5)

       The maximal number of attempts to fork() a child process.

fork_delay (default: 1s)

       The delay between attempts to fork() a child process.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

forward_expansion_filter (default: see postconf -d output)

       Restrict the characters that the  local(8)  delivery  agent  allows  in
       $name  expansions of $forward_path.  Characters outside the allowed set
       are replaced by underscores.

forward_path (default: see postconf -d output)

       The local(8) delivery agent search list for  finding  a  .forward  file
       with  user-specified  delivery methods. The first file that is found is
       used.

       The following $name expansions are  done  on  forward_path  before  the
       search actually happens. The result of $name expansion is filtered with
       the character set that is specified with  the  forward_expansion_filter
       parameter.

       $user  The recipient’s username.

       $shell The recipient’s login shell pathname.

       $home  The recipient’s home directory.

       $recipient
              The full recipient address.

       $extension
              The optional recipient address extension.

       $domain
              The recipient domain.

       $local The entire recipient localpart.

       $recipient_delimiter
              The system-wide recipient address extension delimiter.

       ${name?value}
              Expands to value when $name is non-empty.

       ${name:value}
              Expands to value when $name is empty.

       Instead of $name you can also specify ${name} or $(name).

       Examples:

       forward_path = /var/forward/$user
       forward_path =
           /var/forward/$user/.forward$recipient_delimiter$extension,
           /var/forward/$user/.forward

hash_queue_depth (default: 1)

       The number of subdirectory levels for queue directories listed with the
       hash_queue_names parameter.

       After changing  the  hash_queue_names  or  hash_queue_depth  parameter,
       execute the command "postfix reload".

hash_queue_names (default: deferred, defer)

       The   names  of  queue  directories  that  are  split  across  multiple
       subdirectory levels.

       Before Postfix version 2.2, the  default  list  of  hashed  queues  was
       significantly   larger.   Claims  about  improvements  in  file  system
       technology suggest that hashing of the incoming and active queues is no
       longer  needed.  Fewer  hashed  directories speed up the time needed to
       restart Postfix.

       After changing  the  hash_queue_names  or  hash_queue_depth  parameter,
       execute the command "postfix reload".

header_address_token_limit (default: 10240)

       The  maximal number of address tokens are allowed in an address message
       header. Information that exceeds the limit is discarded.  The limit  is
       enforced by the cleanup(8) server.

header_checks (default: empty)

       Optional  lookup  tables  for  content  inspection  of primary non-MIME
       message headers, as specified in the header_checks(5) manual page.

header_size_limit (default: 102400)

       The maximal amount of memory in bytes for storing a message header.  If
       a  header is larger, the excess is discarded.  The limit is enforced by
       the cleanup(8) server.

helpful_warnings (default: yes)

       Log warnings about  problematic  configuration  settings,  and  provide
       helpful suggestions.

       This feature is available in Postfix 2.0 and later.

home_mailbox (default: empty)

       Optional  pathname of a mailbox file relative to a local(8) user’s home
       directory.

       Specify a pathname ending in "/" for qmail-style delivery.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,   .forward   files,  mailbox_transport,  mailbox_command_maps,
       mailbox_command, home_mailbox, mail_spool_directory, fallback_transport
       and luser_relay.

       Examples:

       home_mailbox = Mailbox
       home_mailbox = Maildir/

hopcount_limit (default: 50)

       The maximal number of Received:  message headers that is allowed in the
       primary message headers. A message that exceeds the limit  is  bounced,
       in order to stop a mailer loop.

html_directory (default: see postconf -d output)

       The  location  of  Postfix  HTML  files  that  describe  how  to build,
       configure or operate a specific Postfix subsystem or feature.

ignore_mx_lookup_error (default: no)

       Ignore DNS MX lookups  that  produce  no  response.   By  default,  the
       Postfix  SMTP  client defers delivery and tries again after some delay.
       This behavior is required by the SMTP standard.

       Specify "ignore_mx_lookup_error = yes" to force a DNS A  record  lookup
       instead. This violates the SMTP standard and can result in mis-delivery
       of mail.

import_environment (default: see postconf -d output)

       The list of environment parameters that a Postfix process  will  import
       from a non-Postfix parent process. Examples of relevant parameters:

       TZ     Needed for sane time keeping on most System-V-ish systems.

       DISPLAY
              Needed for debugging Postfix daemons with an X-windows debugger.

       XAUTHORITY
              Needed for debugging Postfix daemons with an X-windows debugger.

       MAIL_CONFIG
              Needed to make "postfix -c" work.

       Specify   a  list  of  names  and/or  name=value  pairs,  separated  by
       whitespace or comma. The name=value form is supported with Postfix  2.1
       and later.

in_flow_delay (default: 1s)

       Time  to pause before accepting a new message, when the message arrival
       rate exceeds the message delivery rate. This feature is  turned  on  by
       default (it’s disabled on SCO UNIX due to an SCO bug).

       With  the  default  100 SMTP server process limit, "in_flow_delay = 1s"
       limits the mail inflow to 100 messages per second above the  number  of
       messages delivered per second.

       Specify 0 to disable the feature. Valid delays are 0..10.

inet_interfaces (default: all)

       The network interface addresses that this mail system receives mail on.
       Specify "all" to receive mail on all network interfaces (default),  and
       "loopback-only"  to  receive  mail  on loopback network interfaces only
       (Postfix 2.2 and later).  The parameter also controls delivery of  mail
       to user@[ip.address].

       Note 1: you need to stop and start Postfix when this parameter changes.

       Note 2: address information may be enclosed inside [], but this form is
       not recommended here.

       When  inet_interfaces  specifies just one IPv4 and/or IPv6 address that
       is not a loopback address,  the  Postfix  SMTP  client  will  use  this
       address as the IP source address for outbound mail. Support for IPv6 is
       available in Postfix version 2.2 and later.

       On a multi-homed firewall with separate Postfix instances listening  on
       the  "inside"  and "outside" interfaces, this can prevent each instance
       from being able to reach servers on the "other side" of  the  firewall.
       Setting  smtp_bind_address  to 0.0.0.0 avoids the potential problem for
       IPv4, and setting smtp_bind_address6 to :: solves the problem for IPv6.

       A better solution for multi-homed firewalls is to leave inet_interfaces
       at the default value and instead  use  explicit  IP  addresses  in  the
       master.cf  SMTP  server  definitions.  This preserves the SMTP client’s
       loop detection, by ensuring that each side of the firewall  knows  that
       the  other  IP address is still the same host. Setting $inet_interfaces
       to a single IPv4 and/or IPV6 address is primarily useful  with  virtual
       hosting  of  domains  on  secondary  IP addresses, when each IP address
       serves a different domain (and has a different $myhostname setting).

       See also the proxy_interfaces parameter, for network addresses that are
       forwarded to Postfix by way of a proxy or address translator.

       Examples:

       inet_interfaces = all (DEFAULT)
       inet_interfaces = loopback-only (Postfix 2.2 and later)
       inet_interfaces = 127.0.0.1
       inet_interfaces = 127.0.0.1, [::1] (Postfix 2.2 and later)
       inet_interfaces = 192.168.1.2, 127.0.0.1

inet_protocols (default: ipv4)

       The  Internet  protocols  Postfix  will  attempt  to use when making or
       accepting connections.  Specify  one  or  more  of  "ipv4"  or  "ipv6",
       separated  by  whitespace  or  commas.  The form "all" is equivalent to
       "ipv4, ipv6" or "ipv4",  depending  on  whether  the  operating  system
       implements IPv6.

       This feature is available in Postfix version 2.2 and later.

       Note: you MUST stop and start Postfix after changing this parameter.

       On systems that pre-date IPV6_V6ONLY support (RFC 3493), an IPv6 server
       will also accept IPv4 connections, even when IPv4 is  turned  off  with
       the  inet_protocols  parameter.   On  systems with IPV6_V6ONLY support,
       Postfix will use separate server sockets for IPv6 and  IPv4,  and  each
       will accept only connections for the corresponding protocol.

       When  IPv4 support is enabled via the inet_protocols parameter, Postfix
       will to DNS type A record lookups, and will convert IPv4-in-IPv6 client
       IP  addresses  (::ffff:1.2.3.4)  to their original IPv4 form (1.2.3.4).
       The latter is needed on hosts that pre-date  IPV6_V6ONLY  support  (RFC
       3493).

       When  IPv6 support is enabled via the inet_protocols parameter, Postfix
       will do DNS type AAAA record lookups.

       When both IPv4 and IPv6 support are enabled, the  Postfix  SMTP  client
       will attempt to connect via IPv6 before attempting to use IPv4.

       Examples:

       inet_protocols = ipv4 (DEFAULT)
       inet_protocols = all
       inet_protocols = ipv6
       inet_protocols = ipv4, ipv6

initial_destination_concurrency (default: 5)

       The  initial per-destination concurrency level for parallel delivery to
       the same destination. This limit applies to delivery via  smtp(8),  and
       via the pipe(8) and virtual(8) delivery agents.

       Warning:  with concurrency of 1, one bad message can be enough to block
       all mail to a site.

invalid_hostname_reject_code (default: 501)

       The numerical Postfix SMTP server response code when the client HELO or
       EHLO  command  parameter  is  rejected  by  the reject_invalid_hostname
       restriction.

       Do not change this unless you have a complete understanding of RFC 821.

ipc_idle (default: 100s)

       The  time  after  which  a client closes an idle internal communication
       channel.  The purpose is to  allow  servers  to  terminate  voluntarily
       after  they  become  idle.  This  is  used, for example, by the address
       resolving and rewriting clients.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

ipc_timeout (default: 3600s)

       The  time  limit  for sending or receiving information over an internal
       communication channel.   The  purpose  is  to  break  out  of  deadlock
       situations.  If  the  time limit is exceeded the software aborts with a
       fatal error.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

ipc_ttl (default: 1000s)

       The  time  after which a client closes an active internal communication
       channel.  The purpose is to  allow  servers  to  terminate  voluntarily
       after  reaching  their client limit.  This is used, for example, by the
       address resolving and rewriting clients.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

       This feature is available in Postfix 2.1 and later.

line_length_limit (default: 2048)

       Upon  input,  long  lines  are  chopped  up into pieces of at most this
       length; upon delivery, long lines are reconstructed.

lmtp_cache_connection (default: yes)

       Keep Postfix LMTP client connections open for up to $max_idle  seconds.
       When  the  LMTP  client  receives a request for the same connection the
       connection is reused.

       The effectiveness of cached  connections  will  be  determined  by  the
       number  of LMTP servers in use, and the concurrency limit specified for
       the LMTP client.  Cached  connections  are  closed  under  any  of  the
       following conditions:

       ·      The  LMTP  client  idle  time  limit  is reached.  This limit is
              specified with the Postfix max_idle configuration parameter.

       ·      A delivery request specifies a different  destination  than  the
              one currently cached.

       ·      The  per-process  limit  on  the  number of delivery requests is
              reached.  This limit  is  specified  with  the  Postfix  max_use
              configuration parameter.

       ·      Upon  the  onset  of  another  delivery request, the LMTP server
              associated with the current session does not respond to the RSET
              command.

       Most  of  these  limitations will be removed after Postfix implements a
       connection cache that is shared among multiple LMTP client programs.

lmtp_connect_timeout (default: 0s)

       The LMTP client time limit for completing a  TCP  connection,  or  zero
       (use the operating system built-in time limit).  When no connection can
       be made within the deadline, the LMTP client tries the next address  on
       the mail exchanger list.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

       Example:

       lmtp_connect_timeout = 30s

lmtp_data_done_timeout (default: 600s)

       The LMTP client time limit for sending the LMTP ".", and for  receiving
       the server response.  When no response is received within the deadline,
       a warning is logged that the mail may be delivered multiple times.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

lmtp_data_init_timeout (default: 120s)

       The  LMTP  client time limit for sending the LMTP DATA command, and for
       receiving the server response.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

lmtp_data_xfer_timeout (default: 180s)

       The  LMTP client time limit for sending the LMTP message content.  When
       the connection stalls for more than  $lmtp_data_xfer_timeout  the  LMTP
       client terminates the transfer.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_destination_concurrency_limit (default:

       $default_destination_concurrency_limit)
       The  maximal  number of parallel deliveries to the same destination via
       the lmtp message delivery transport. This  limit  is  enforced  by  the
       queue  manager.  The message delivery transport name is the first field
       in the entry in the master.cf file.

lmtp_destination_recipient_limit (default:

       $default_destination_recipient_limit)
       The  maximal  number  of  recipients  per delivery via the lmtp message
       delivery transport. This limit is enforced by the  queue  manager.  The
       message  delivery transport name is the first field in the entry in the
       master.cf file.

       Setting this  parameter  to  a  value  of  1  changes  the  meaning  of
       lmtp_destination_concurrency_limit  from  concurrency  per  domain into
       concurrency per recipient.

lmtp_lhlo_timeout (default: 300s)

       The LMTP client time limit for  receiving  the  LMTP  greeting  banner.
       When the server drops the connection without sending a greeting banner,
       or when it sends no greeting  banner  within  the  deadline,  the  LMTP
       client tries the next address on the mail exchanger list.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_mail_timeout (default: 300s)

       The LMTP client time limit for sending the MAIL FROM command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_quit_timeout (default: 300s)

       The LMTP client time limit  for  sending  the  QUIT  command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_rcpt_timeout (default: 300s)

       The LMTP client time limit for sending the RCPT  TO  command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_rset_timeout (default: 20s)

       The LMTP client time limit  for  sending  the  RSET  command,  and  for
       receiving  the  server response. The LMTP client sends RSET in order to
       finish a recipient address probe, or to verify that a cached connection
       is still alive.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

lmtp_sasl_auth_enable (default: no)

       Enable SASL authentication in the Postfix LMTP client.

lmtp_sasl_password_maps (default: empty)

       Optional LMTP client lookup tables with one username:password entry per
       host  or  domain.   If a remote host or domain has no username:password
       entry, then the Postfix LMTP client will not attempt to authenticate to
       the remote host.

lmtp_sasl_security_options (default: noplaintext, noanonymous)

       What  authentication  mechanisms  the Postfix LMTP client is allowed to
       use.  The  list  of  available  authentication  mechanisms  is   system
       dependent.

       noplaintext
              Disallow authentication methods that use plaintext passwords.

       noactive
              Disallow  authentication  methods  that  are  vulnerable to non-
              dictionary active attacks.

       nodictionary
              Disallow authentication methods that are vulnerable  to  passive
              dictionary attack.

       noanonymous
              Disallow anonymous logins.

       Example:

       lmtp_sasl_security_options = noplaintext

lmtp_send_xforward_command (default: no)

       Send  an  XFORWARD command to the LMTP server when the LMTP LHLO server
       response announces XFORWARD support.  This allows an  lmtp(8)  delivery
       agent,  used for content filter message injection, to forward the name,
       address, protocol and HELO name of the original client to  the  content
       filter and downstream queuing LMTP server.  Before you change the value
       to yes, it is best to make sure that your content filter supports  this
       command.

       This feature is available in Postfix 2.1 and later.

lmtp_skip_quit_response (default: no)

       Wait for the response to the LMTP QUIT command.

lmtp_tcp_port (default: 24)

       The default TCP port that the Postfix LMTP client connects to.

lmtp_xforward_timeout (default: 300s)

       The  LMTP  client  time limit for sending the XFORWARD command, and for
       receiving the server response.

       In case of problems the client does NOT try the  next  address  on  the
       mail exchanger list.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

       This feature is available in Postfix 2.1 and later.

local_command_shell (default: empty)

       Optional shell program for local(8) delivery  to  non-Postfix  command.
       By  default,  non-Postfix  commands are executed directly; commands are
       given to given to /bin/sh only when they contain shell meta  characters
       or shell built-in commands.

       "sendmail’s  restricted  shell" (smrsh) is what most people will use in
       order to restrict what programs can be run  from  e.g.  .forward  files
       (smrsh is part of the Sendmail distribution).

       Note:  when  a  shell program is specified, it is invoked even when the
       command contains no shell built-in commands or meta characters.

       Example:

       local_command_shell = /some/where/smrsh -c

local_destination_concurrency_limit (default: 2)

       The maximal number of parallel deliveries via the local  mail  delivery
       transport        to        the        same        recipient       (when
       "local_destination_recipient_limit =  1")  or  the  maximal  number  of
       parallel    deliveries    to    the    same    local    domain    (when
       "local_destination_recipient_limit > 1"). This limit is enforced by the
       queue  manager.  The message delivery transport name is the first field
       in the entry in the master.cf file.

       A low limit of 2 is recommended, just in case someone has an  expensive
       shell  command  in a .forward file or in an alias (e.g., a mailing list
       manager).  You don’t want to run lots of those at the same time.

local_destination_recipient_limit (default: 1)

       The maximal number of recipients per message  delivery  via  the  local
       mail  delivery  transport. This limit is enforced by the queue manager.
       The message delivery transport name is the first field in the entry  in
       the master.cf file.

       Setting  this  parameter  to  a  value  >  1  changes  the  meaning  of
       local_destination_concurrency_limit from concurrency per recipient into
       concurrency per domain.

local_header_rewrite_clients (default: permit_inet_interfaces)

       Rewrite  message header addresses in mail from these clients and update
       incomplete addresses with the domain name in  $myorigin  or  $mydomain;
       either  don’t  rewrite  message  headers  from other clients at all, or
       rewrite message headers and update incomplete addresses with the domain
       specified in the remote_header_rewrite_domain parameter.

       See  the  append_at_myorigin  and  append_dot_mydomain  parameters  for
       details of how domain names are appended to incomplete addresses.

       Specify a list of zero or more of the following:

        permit_inet_interfaces
              Append the domain name in $myorigin or $mydomain when the client
              IP address matches $inet_interfaces. This is enabled by default.

        permit_mynetworks
              Append the domain name in $myorigin or $mydomain when the client
              IP  address  matches  any  network  or network address listed in
              $mynetworks. This setting will not prevent  remote  mail  header
              address rewriting when mail from a remote client is forwarded by
              a neighboring system.

        permit_sasl_authenticated
              Append the domain name in $myorigin or $mydomain when the client
              is  successfully authenticated via the RFC 2554 (AUTH) protocol.

        permit_tls_clientcerts
              Append the domain name in $myorigin or $mydomain when the client
              TLS   certificate  is  successfully  verified,  and  the  client
              certificate fingerprint is listed in $relay_clientcerts.

        permit_tls_all_clientcerts
              Append the domain name in $myorigin or $mydomain when the client
              TLS  certificate is successfully verified, regardless of whether
              it is listed on the server, and  regardless  of  the  certifying
              authority.

        check_address_map type:table

        type:table
              Append the domain name in $myorigin or $mydomain when the client
              IP address matches  the  specified  lookup  table.   The  lookup
              result  is  ignored,  and  no  subnet  lookup  is  done. This is
              suitable for, e.g., pop-before-smtp lookup tables.

       Examples:

       The Postfix < 2.2 backwards compatible setting: always rewrite  message
       headers,   and  always  append  my  own  domain  to  incomplete  header
       addresses.

           local_header_rewrite_clients = static:all

       The purist (and default) setting: rewrite headers  only  in  mail  from
       Postfix sendmail and in SMTP mail from this machine.

           local_header_rewrite_clients = permit_inet_interfaces

       The intermediate setting: rewrite header addresses and append $myorigin
       or $mydomain information only with mail  from  Postfix  sendmail,  from
       local clients, or from authorized SMTP clients.

       Note:  this  setting  will  not  prevent  remote  mail  header  address
       rewriting when mail from a remote client is forwarded by a  neighboring
       system.

           local_header_rewrite_clients = permit_mynetworks,
               permit_sasl_authenticated permit_tls_clientcerts
               check_address_map hash:/etc/postfix/pop-before-smtp

local_recipient_maps (default: proxy:unix:passwd.byname $alias_maps)

       Lookup  tables  with  all  names  or  addresses  of local recipients: a
       recipient address is local  when  its  domain  matches  $mydestination,
       $inet_interfaces  or $proxy_interfaces.  Specify @domain as a wild-card
       for domains that do not have  a  valid  recipient  list.   Technically,
       tables  listed  with  $local_recipient_maps  are used as lists: Postfix
       needs to know only if a lookup string is found or not, but it does  not
       use the result from table lookup.

       If  this  parameter  is  non-empty (the default), then the Postfix SMTP
       server will reject mail for unknown local users.

       To turn off local  recipient  checking  in  the  Postfix  SMTP  server,
       specify "local_recipient_maps =" (i.e. empty).

       The  default  setting  assumes  that  you use the default Postfix local
       delivery  agent  for  local  delivery.   You   need   to   update   the
       local_recipient_maps setting if:

       ·      You redefine the local delivery agent in master.cf.

       ·      You redefine the "local_transport" setting in main.cf.

       ·      You    use    the    "luser_relay",    "mailbox_transport",   or
              "fallback_transport" feature of the  Postfix  local(8)  delivery
              agent.

       Details are described in the LOCAL_RECIPIENT_README file.

       Beware:  if  the  Postfix SMTP server runs chrooted, you need to access
       the passwd file via the  proxymap(8)  service,  in  order  to  overcome
       chroot  access restrictions. The alternative, maintaining a copy of the
       system password file in the chroot jail is not practical.

       Examples:

       local_recipient_maps =

local_transport (default: local:$myhostname)

       The  default  mail  delivery   transport   for   domains   that   match
       $mydestination,    $inet_interfaces    or    $proxy_interfaces.    This
       information can be overruled with the transport(5) table.

       By default, local mail is delivered to the  transport  called  "local",
       which is just the name of a service that is defined the master.cf file.

       Specify a string of the form transport:nexthop, where transport is  the
       name  of  a mail delivery transport defined in master.cf.  The :nexthop
       part is optional.  For more details see the transport(5) manual page.

       Beware: if you override the default local delivery agent then you  need
       to  review  the  LOCAL_RECIPIENT_README  document,  otherwise  the SMTP
       server may reject mail for local recipients.

luser_relay (default: empty)

       Optional catch-all destination for  unknown  local(8)  recipients.   By
       default,   mail   for   unknown   recipients   in  domains  that  match
       $mydestination, $inet_interfaces or $proxy_interfaces  is  returned  as
       undeliverable.

       The following $name expansions are done on luser_relay:

       $domain
              The recipient domain.

       $extension
              The recipient address extension.

       $home  The recipient’s home directory.

       $local The entire recipient address localpart.

       $recipient
              The full recipient address.

       $recipient_delimiter
              The system-wide recipient address extension delimiter.

       $shell The recipient’s login shell.

       $user  The recipient username.

       ${name?value}
              Expands to value when $name has a non-empty value.

       ${name:value}
              Expands to value when $name has an empty value.

       Instead of $name you can also specify ${name} or $(name).

       Note: luser_relay works only for the Postfix local(8) delivery agent.

       Note:  if  you  use  this feature for accounts not in the UNIX password
       file, then you must specify "local_recipient_maps ="  (i.e.  empty)  in
       the  main.cf  file,  otherwise the Postfix SMTP server will reject mail
       for non-UNIX accounts with "User unknown in local recipient table".

       Examples:

       luser_relay = $user@other.host
       luser_relay = $local@other.host
       luser_relay = admin+$local

mail_name (default: Postfix)

       The mail system name that is displayed in  Received:  headers,  in  the
       SMTP greeting banner, and in bounced mail.

mail_owner (default: postfix)

       The  UNIX  system  account that owns the Postfix queue and most Postfix
       daemon processes.  Specify the name of a user  account  that  does  not
       share  a  group  with  other  accounts  and that owns no other files or
       processes on the  system.   In  particular,  don’t  specify  nobody  or
       daemon.  PLEASE USE A DEDICATED USER ID AND GROUP ID.

       When  this  parameter value is changed you need to re-run "postfix set-
       permissions" (with Postfix 2.0 and earlier:  "/etc/postfix/post-install
       set-permissions".

mail_release_date (default: see postconf -d output)

       The Postfix release date, in "YYYYMMDD" format.

mail_spool_directory (default: see postconf -d output)

       The directory where local(8) UNIX-style mailboxes are kept. The default
       setting depends on the system type. Specify a  name  ending  in  /  for
       maildir-style delivery.

       Note:  maildir  delivery  is done with the privileges of the recipient.
       If you use the mail_spool_directory setting for maildir style delivery,
       then  you  must  create  the  top-level  maildir  directory in advance.
       Postfix will not create it.

       Examples:

       mail_spool_directory = /var/mail
       mail_spool_directory = /var/spool/mail

mail_version (default: see postconf -d output)

       The  version  of  the  mail   system.   Stable   releases   are   named
       major.minor.patchlevel.  Experimental releases also include the release
       date. The version string can be used in, for example, the SMTP greeting
       banner.

mailbox_command (default: empty)

       Optional  external  command that the local(8) delivery agent should use
       for mailbox delivery.  The command is run with  the  user  ID  and  the
       primary  group  ID  privileges  of  the  recipient.  Exception: command
       delivery for root executes with $default_privs privileges.  This is not
       a  problem, because 1) mail for root should always be aliased to a real
       user and 2) don’t log in as root, use "su" instead.

       The following environment variables are exported to the command:

       CLIENT_ADDRESS
              Remote client network address.  Available  in  Postfix  2.2  and
              later.

       CLIENT_HELO
              Remote  client  EHLO command parameter. Available in Postfix 2.2
              and later.

       CLIENT_HOSTNAME
              Remote client hostname. Available in Postfix 2.2 and later.

       CLIENT_PROTOCOL
              Remote client protocol. Available in Postfix 2.2 and later.

       DOMAIN The domain part of the recipient address.

       EXTENSION
              The optional address extension.

       HOME   The recipient home directory.

       LOCAL  The recipient address localpart.

       LOGNAME
              The recipient’s username.

       RECIPIENT
              The full recipient address.

       SASL_METHOD
              SASL authentication method specified in the remote  client  AUTH
              command. Available in Postfix 2.2 and later.

       SASL_SENDER
              SASL  sender  address  specified  in the remote client MAIL FROM
              command. Available in Postfix 2.2 and later.

       SASL_USER
              SASL username specified  in  the  remote  client  AUTH  command.
              Available in Postfix 2.2 and later.

       SENDER The full sender address.

       SHELL  The recipient’s login shell.

       USER   The recipient username.

       Unlike  other  Postfix  configuration  parameters,  the mailbox_command
       parameter is not subjected to $name substitutions. This is to  make  it
       easier to specify shell syntax (see example below).

       If you can, avoid shell meta characters because they will force Postfix
       to run an expensive shell process. If you’re  delivering  via  Procmail
       then  running  a  shell won’t make a noticeable difference in the total
       cost.

       Note: if you use the mailbox_command feature to  deliver  mail  system-
       wide,  you  must  set up an alias that forwards mail for root to a real
       user.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,   .forward   files,  mailbox_transport,  mailbox_command_maps,
       mailbox_command, home_mailbox, mail_spool_directory, fallback_transport
       and luser_relay.

       Examples:

       mailbox_command = /some/where/procmail
       mailbox_command = /some/where/procmail -a "$EXTENSION"
       mailbox_command = /some/where/maildrop -d "$USER"
               -f "$SENDER" "$EXTENSION"

mailbox_command_maps (default: empty)

       Optional  lookup tables with per-recipient external commands to use for
       local(8) mailbox delivery.  Behavior is as with mailbox_command.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,   .forward   files,  mailbox_transport,  mailbox_command_maps,
       mailbox_command, home_mailbox, mail_spool_directory, fallback_transport
       and luser_relay.

mailbox_delivery_lock (default: see postconf -d output)

       How  to  lock a UNIX-style local(8) mailbox before attempting delivery.
       For a list of available file locking methods,  use  the  "postconf  -l"
       command.

       This  setting  is  ignored  with  maildir  style delivery, because such
       deliveries are safe without explicit locks.

       Note: The dotlock method requires that the recipient  UID  or  GID  has
       write access to the parent directory of the mailbox file.

       Note: the default setting of this parameter is system dependent.

mailbox_size_limit (default: 51200000)

       The maximal size of any local(8) individual mailbox or maildir file, or
       zero (no limit).  In fact, this limits the size of  any  file  that  is
       written  to  upon  local  delivery, including files written by external
       commands that are executed by the local(8) delivery agent.

       This limit must not be smaller than the message size limit.

mailbox_transport (default: empty)

       Optional message delivery transport that the  local(8)  delivery  agent
       should use for mailbox delivery to all local recipients, whether or not
       they are found in the UNIX passwd database.

       The precedence of local(8) delivery  features  from  high  to  low  is:
       aliases,   .forward   files,  mailbox_transport,  mailbox_command_maps,
       mailbox_command, home_mailbox, mail_spool_directory, fallback_transport
       and luser_relay.

mailq_path (default: see postconf -d output)

       Sendmail   compatibility  feature  that  specifies  where  the  Postfix
       mailq(1) command is installed. This command can be  used  to  list  the
       Postfix mail queue.

manpage_directory (default: see postconf -d output)

       Where the Postfix manual pages are installed.

maps_rbl_domains (default: empty)

       Obsolete feature: use the reject_rbl_client feature instead.

maps_rbl_reject_code (default: 554)

       The  numerical  Postfix  SMTP  server  response code when a remote SMTP
       client    request    is    blocked    by     the     reject_rbl_client,
       reject_rhsbl_client,   reject_rhsbl_sender   or  reject_rhsbl_recipient
       restriction.

       Do not change this unless you have a complete understanding of RFC 821.

masquerade_classes (default: envelope_sender, header_sender, header_recipient)

       What addresses are subject to address masquerading.

       By  default,  address  masquerading  is  limited  to  envelope   sender
       addresses,  and  to header sender and header recipient addresses.  This
       allows you to use address masquerading on a mail  gateway  while  still
       being able to forward mail to users on individual machines.

       Specify   zero   or   more   of:  envelope_sender,  envelope_recipient,
       header_sender, header_recipient

masquerade_domains (default: empty)

       Optional list of domains whose subdomain structure will be stripped off
       in email addresses.

       The  list is processed left to right, and processing stops at the first
       match.  Thus,

           masquerade_domains = foo.example.com example.com

       strips "user@any.thing.foo.example.com" to "user@foo.example.com",  but
       strips "user@any.thing.else.example.com" to "user@example.com".

       A  domain  name  prefixed with ! means do not masquerade this domain or
       its subdomains. Thus,

           masquerade_domains = !foo.example.com example.com

       does      not      change      "user@any.thing.foo.example.com"      or
       "user@foo.example.com", but strips "user@any.thing.else.example.com" to
       "user@example.com".

       Note: with Postfix version 2.2,  message  header  address  masquerading
       happens only when message header address rewriting is enabled:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The  message  is  received  from  a  network client that matches
              $local_header_rewrite_clients,

       ·      The  message   is   received   from   the   network,   and   the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To    get    the    behavior    before     Postfix     2.2,     specify
       "local_header_rewrite_clients = static:all".

       Example:

       masquerade_domains = $mydomain

masquerade_exceptions (default: empty)

       Optional  list  of  user  names  that  are  not  subjected  to  address
       masquerading, even when their address matches $masquerade_domains.

       By default, address masquerading makes no exceptions.

       Specify a list of user names, "/file/name"  or  "type:table"  patterns,
       separated  by  commas  and/or  whitespace.  The list is matched left to
       right, and the search stops on the  first  match.  Specify  "!name"  to
       exclude a name from the list. A "/file/name" pattern is replaced by its
       contents; a "type:table" lookup table is matched when a name matches  a
       lookup  key  (the  lookup  result  is ignored).  Continue long lines by
       starting the next line with whitespace.

       Examples:

       masquerade_exceptions = root, mailer-daemon
       masquerade_exceptions = root

max_idle (default: 100s)

       The maximum amount of time that an idle Postfix  daemon  process  waits
       for the next service request before exiting.  This parameter is ignored
       by the Postfix queue manager.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

max_use (default: 100)

       The  maximal  number  of  connection  requests  before a Postfix daemon
       process terminates. This parameter is  ignored  by  the  Postfix  queue
       manager and by other long-lived Postfix daemon processes.

maximal_backoff_time (default: 4000s)

       The maximal time between attempts to deliver a deferred message.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

maximal_queue_lifetime (default: 5d)

       The maximal time a  message  is  queued  before  it  is  sent  back  as
       undeliverable.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is d (days).

       Specify 0 when mail delivery should be tried only once.

message_size_limit (default: 10240000)

       The maximal size in bytes of a message, including envelope information.

mime_boundary_length_limit (default: 2048)

       The  maximal  length  of  MIME  multipart  boundary  strings.  The MIME
       processor is unable to distinguish between boundary strings that do not
       differ in the first $mime_boundary_length_limit characters.

       This feature is available in Postfix 2.0 and later.

mime_header_checks (default: $header_checks)

       Optional  lookup  tables for content inspection of MIME related message
       headers, as described in the header_checks(5) manual page.

       This feature is available in Postfix 2.0 and later.

mime_nesting_limit (default: 100)

       The maximal recursion  level  that  the  MIME  processor  will  handle.
       Postfix refuses mail that is nested deeper than the specified limit.

       This feature is available in Postfix 2.0 and later.

minimal_backoff_time (default: 1000s)

       The  minimal time between attempts to deliver a deferred message.  This
       parameter also limits the time an unreachable destination  is  kept  in
       the short-term, in-memory, destination status cache.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

multi_recipient_bounce_reject_code (default: 550)

       The numerical Postfix SMTP server response  code  when  a  remote  SMTP
       client   request   is   blocked  by  the  reject_multi_recipient_bounce
       restriction.

       Do not change this unless you have a complete understanding of RFC 821.

       This feature is available in Postfix 2.1 and later.

mydestination (default: $myhostname, localhost.$mydomain, localhost)

       The  list  of  domains that are delivered via the $local_transport mail
       delivery transport. By default this is the  Postfix  local(8)  delivery
       agent  which  looks  up all recipients in /etc/passwd and /etc/aliases.
       The    SMTP    server    validates     recipient     addresses     with
       $local_recipient_maps and rejects non-existent recipients. See also the
       local domain class in the ADDRESS_CLASS_README file.

       The default mydestination value specifies names for the  local  machine
       only.  On a mail domain gateway, you should also include $mydomain.

       The   $local_transport  delivery  method  is  also  selected  for  mail
       addressed to user@[the.net.work.address] of the  mail  system  (the  IP
       addresses  specified  with  the  inet_interfaces  and  proxy_interfaces
       parameters).

       Warnings:

       ·      Do not specify the names of virtual domains - those domains  are
              specified elsewhere. See VIRTUAL_README for more information.

       ·      Do  not specify the names of domains that this machine is backup
              MX host for. See STANDARD_CONFIGURATION_README for how to set up
              backup MX hosts.

       ·      By  default, the Postfix SMTP server rejects mail for recipients
              not listed with the  local_recipient_maps  parameter.   See  the
              postconf(5) manual for a description of the local_recipient_maps
              and unknown_local_recipient_reject_code parameters.

       Specify a list of host or domain names,  "/file/name"  or  "type:table"
       patterns, separated by commas and/or whitespace. A "/file/name" pattern
       is replaced by its contents; a "type:table"  lookup  table  is  matched
       when  a  name  matches  a  lookup  key  (the lookup result is ignored).
       Continue long lines by starting the next line with whitespace.

       Examples:

       mydestination = $myhostname, localhost.$mydomain $mydomain
       mydestination = $myhostname, localhost.$mydomain www.$mydomain, ftp.$mydomain

mydomain (default: see postconf -d output)

       The internet domain name of this mail system.  The default  is  to  use
       $myhostname  minus the first component.  $mydomain is used as a default
       value for many other configuration parameters.

       Example:

       mydomain = domain.tld

myhostname (default: see postconf -d output)

       The internet hostname of this mail system. The default is  to  use  the
       fully-qualified  domain name from gethostname(). $myhostname is used as
       a default value for many other configuration parameters.

       Example:

       myhostname = host.domain.tld

mynetworks (default: see postconf -d output)

       The list of "trusted" SMTP  clients  that  have  more  privileges  than
       "strangers".

       In particular, "trusted" SMTP clients are allowed to relay mail through
       Postfix.  See the smtpd_recipient_restrictions parameter description in
       the postconf(5) manual.

       You  can specify the list of "trusted" network addresses by hand or you
       can let Postfix do  it  for  you  (which  is  the  default).   See  the
       description of the mynetworks_style parameter for more information.

       If  you  specify  the  mynetworks  list  by  hand,  Postfix ignores the
       mynetworks_style setting.

       Specify a  list  of  network  addresses  or  network/netmask  patterns,
       separated  by commas and/or whitespace. Continue long lines by starting
       the next line with whitespace.

       The netmask specifies the number of bits in the network part of a  host
       address.   You  can also specify "/file/name" or "type:table" patterns.
       A "/file/name" pattern is replaced  by  its  contents;  a  "type:table"
       lookup table is matched when a table entry matches a lookup string (the
       lookup result is ignored).

       The list is matched left to right, and the search stops  on  the  first
       match.   Specify "!pattern" to exclude an address or network block from
       the list.

       Note: IP version 6 address information must be specified inside  []  in
       the  mynetworks  value,  and  in files specified with "/file/name".  IP
       version 6 addresses contain the ":" character, and would  otherwise  be
       confused with a "type:table" pattern.

       Examples:

       mynetworks = 127.0.0.0/8 168.100.189.0/28
       mynetworks = !192.168.0.1, 192.168.0.0/28
       mynetworks = 127.0.0.0/8 168.100.189.0/28 [::1]/128 [2001:240:5c7::]/64
       mynetworks = $config_directory/mynetworks
       mynetworks = hash:/etc/postfix/network_table

mynetworks_style (default: subnet)

       The  method to generate the default value for the mynetworks parameter.
       This is the list of trusted networks for relay access control etc.

       ·      Specify "mynetworks_style = host" when  Postfix  should  "trust"
              only the local machine.

       ·      Specify  "mynetworks_style = subnet" when Postfix should "trust"
              SMTP clients in the same IP subnetworks as  the  local  machine.
              On  Linux,  this  works correctly only with interfaces specified
              with the "ifconfig" command.

       ·      Specify "mynetworks_style = class" when Postfix  should  "trust"
              SMTP  clients  in  the same IP class A/B/C networks as the local
              machine.  Don’t do this with a dialup  site  -  it  would  cause
              Postfix  to  "trust"  your  entire provider’s network.  Instead,
              specify an explicit mynetworks list by hand, as  described  with
              the mynetworks configuration parameter.

myorigin (default: $myhostname)

       The domain name that locally-posted mail appears to come from, and that
       locally posted mail is  delivered  to.  The  default,  $myhostname,  is
       adequate  for small sites.  If you run a domain with multiple machines,
       you should (1) change this to $mydomain and (2) set  up  a  domain-wide
       alias database that aliases each user to user@that.users.mailhost.

       Example:

       myorigin = $mydomain

nested_header_checks (default: $header_checks)

       Optional  lookup  tables  for  content  inspection  of non-MIME message
       headers in attached messages,  as  described  in  the  header_checks(5)
       manual page.

       This feature is available in Postfix 2.0 and later.

newaliases_path (default: see postconf -d output)

       Sendmail  compatibility  feature  that  specifies  the  location of the
       newaliases(1) command. This command can be used to rebuild the local(8)
       aliases(5) database.

non_fqdn_reject_code (default: 504)

       The  numerical  Postfix SMTP server reply code when a client request is
       rejected by  the  reject_non_fqdn_hostname,  reject_non_fqdn_sender  or
       reject_non_fqdn_recipient restriction.

notify_classes (default: resource, software)

       The  list  of  error  classes  that are reported to the postmaster. The
       default is to report only the most serious problems. The  paranoid  may
       wish  to  turn on the policy (UCE and mail relaying) and protocol error
       (broken mail software) reports.

       The error classes are:

       bounce (also implies 2bounce)
              Send the postmaster copies of the headers of bounced  mail,  and
              send transcripts of SMTP sessions when Postfix rejects mail. The
              notification  is  sent  to  the  address  specified   with   the
              bounce_notice_recipient    configuration   parameter   (default:
              postmaster).

       2bounce
              Send  undeliverable  bounced  mail  to   the   postmaster.   The
              notification   is   sent  to  the  address  specified  with  the
              2bounce_notice_recipient   configuration   parameter   (default:
              postmaster).

       delay  Send  the  postmaster copies of the headers of delayed mail. The
              notification  is  sent  to  the  address  specified   with   the
              delay_notice_recipient    configuration    parameter   (default:
              postmaster).

       policy Send the postmaster a transcript of  the  SMTP  session  when  a
              client  request  was  rejected  because  of  (UCE)  policy.  The
              notification  is  sent  to  the  address  specified   with   the
              error_notice_recipient    configuration    parameter   (default:
              postmaster).

       protocol
              Send the postmaster a transcript of the SMTP session in case  of
              client  or  server  protocol errors. The notification is sent to
              the   address   specified   with   the    error_notice_recipient
              configuration parameter (default: postmaster).

       resource
              Inform  the  postmaster  of  mail  not delivered due to resource
              problems.  The notification is sent  to  the  address  specified
              with    the   error_notice_recipient   configuration   parameter
              (default: postmaster).

       software
              Inform the postmaster of mail  not  delivered  due  to  software
              problems.   The  notification  is  sent to the address specified
              with   the   error_notice_recipient   configuration    parameter
              (default: postmaster).

       Examples:

       notify_classes = bounce, delay, policy, protocol, resource, software
       notify_classes = 2bounce, resource, software

owner_request_special (default: yes)

       Give  special  treatment to owner-listname and listname-request address
       localparts: don’t split such addresses when the recipient_delimiter  is
       set to "-".  This feature is useful for mailing lists.

parent_domain_matches_subdomains (default: see postconf -d output)

       What  Postfix  features match subdomains of "domain.tld" automatically,
       instead of  requiring  an  explicit  ".domain.tld"  pattern.   This  is
       planned  backwards compatibility:  eventually, all Postfix features are
       expected to require explicit  ".domain.tld"  style  patterns  when  you
       really want to match subdomains.

permit_mx_backup_networks (default: empty)

       Restrict  the  use  of the permit_mx_backup SMTP access feature to only
       domains whose primary MX hosts match the listed networks.

pickup_service_name (default: pickup)

       The name of the pickup(8) service. This service  picks  up  local  mail
       submissions from the Postfix maildrop queue.

       This feature is available in Postfix 2.0 and later.

prepend_delivered_header (default: command, file, forward)

       The message delivery contexts where the Postfix local(8) delivery agent
       prepends a Delivered-To:  message header.

       By default, the Postfix local delivery agent prepends  a  Delivered-To:
       header  when  forwarding mail and when delivering to file (mailbox) and
       command. Turning off the Delivered-To: header when forwarding  mail  is
       not recommended.

       Specify zero or more of forward, file, or command.

       Example:

       prepend_delivered_header = forward

process_id (read-only)

       The process ID of a Postfix command or daemon process.

process_id_directory (default: pid)

       The  location  of Postfix PID files relative to $queue_directory.  This
       is a read-only parameter.

process_name (read-only)

       The process name of a Postfix command or daemon process.

propagate_unmatched_extensions (default: canonical, virtual)

       What address lookup tables copy an address extension  from  the  lookup
       key to the lookup result.

       For example, with a virtual(5) mapping of "joe@domain -> joe.user", the
       address "joe+foo@domain" would rewrite to "joe.user+foo".

       Specify zero or more of canonical, virtual, alias, forward, include  or
       generic.  These  cause address extension propagation with canonical(5),
       virtual(5), and aliases(5) maps, with local(8) .forward  and  :include:
       file lookups, and with smtp(8) generic maps, respectively.

       Note:  enabling this feature for types other than canonical and virtual
       is likely to cause problems when mail  is  forwarded  to  other  sites,
       especially with mail that is sent to a mailing list exploder address.

       Examples:

       propagate_unmatched_extensions = canonical, virtual, alias,
               forward, include
       propagate_unmatched_extensions = canonical, virtual

proxy_interfaces (default: empty)

       The  network interface addresses that this mail system receives mail on
       by way of a proxy or network address translation unit.

       This feature is available in Postfix 2.0 and later.

       You must specify your "outside" proxy/NAT addresses when your system is
       a  backup MX host for other domains, otherwise mail delivery loops will
       happen when the primary MX host is down.

       Example:

       proxy_interfaces = 1.2.3.4

proxy_read_maps (default: see postconf -d output)

       The lookup tables that the proxymap(8) server  is  allowed  to  access.
       Table  references  that  don’t  begin  with  proxy:  are  ignored.  The
       proxymap(8) table accesses are read-only.

       This feature is available in Postfix 2.0 and later.

qmgr_clog_warn_time (default: 300s)

       The minimal delay between  warnings  that  a  specific  destination  is
       clogging up the Postfix active queue. Specify 0 to disable.

       This feature is enabled with the helpful_warnings parameter.

       This feature is available in Postfix 2.0 and later.

qmgr_fudge_factor (default: 100)

       Obsolete feature: the percentage of delivery resources that a busy mail
       system will use up for delivery of a large mailing  list message.

       This feature exists only in the oqmgr(8) old queue manager. The current
       queue manager solves the problem in a better way.

qmgr_message_active_limit (default: 20000)

       The maximal number of messages in the active queue.

qmgr_message_recipient_limit (default: 20000)

       The  maximal  number  of recipients held in memory by the Postfix queue
       manager, and the maximal size of the size of the short-term,  in-memory
       "dead" destination status cache.

qmgr_message_recipient_minimum (default: 10)

       The  minimal number of in-memory recipients for any message. This takes
       priority over any other in-memory recipient limits  (i.e.,  the  global
       qmgr_message_recipient_limit and the per transport _recipient_limit) if
       necessary. The minimum value allowed for this parameter is 1.

qmqpd_authorized_clients (default: empty)

       What clients are allowed to connect to the QMQP server port.

       By default, no client is allowed to use the service.  This  is  because
       the QMQP server will relay mail to any destination.

       Specify  a  list  of  client  patterns. A list pattern specifies a host
       name, a domain name, an internet address, or  a  network/mask  pattern,
       where  the mask specifies the number of bits in the network part.  When
       a pattern specifies a file name, its contents are substituted  for  the
       file  name; when a pattern is a "type:table" table specification, table
       lookup is used instead.

       Patterns are separated by whitespace and/or commas. In order to reverse
       the  result,  precede a non-file name pattern with an exclamation point
       (!).

       Example:

       qmqpd_authorized_clients = !192.168.0.1, 192.168.0.0/24

qmqpd_error_delay (default: 1s)

       How long the QMQP server will pause before sending a negative reply  to
       the  client. The purpose is to slow down confused or malicious clients.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

qmqpd_timeout (default: 300s)

       The  time  limit for sending or receiving information over the network.
       If a read or  write  operation  blocks  for  more  than  $qmqpd_timeout
       seconds the QMQP server gives up and disconnects.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

queue_directory (default: see postconf -d output)

       The location of the Postfix top-level queue directory. This is the root
       directory of Postfix daemon processes that run chrooted.

queue_file_attribute_count_limit (default: 100)

       The  maximal  number of (name=value) attributes that may be stored in a
       Postfix queue file. The limit is enforced by the cleanup(8) server.

       This feature is available in Postfix 2.0 and later.

queue_minfree (default: 0)

       The minimal amount of free space in bytes in the queue file system that
       is  needed  to receive mail.  This is currently used by the SMTP server
       to decide if it will accept any mail at all.

       By default, the Postfix 2.1 SMTP server rejects MAIL FROM commands when
       the  amount  of  free  space  is less than 1.5*$message_size_limit.  To
       specify a higher minimum free  space  limit,  specify  a  queue_minfree
       value that is at least 1.5*$message_size_limit.

       With  Postfix  versions  2.0 and earlier, a queue_minfree value of zero
       means there is no minimum required amount of free space.

queue_run_delay (default: 1000s)

       The time between deferred queue scans by the queue manager.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

queue_service_name (default: qmgr)

       The name of the qmgr(8) service. This service manages the Postfix queue
       and schedules delivery requests.

       This feature is available in Postfix 2.0 and later.

rbl_reply_maps (default: empty)

       Optional lookup tables with RBL  response  templates.  The  tables  are
       indexed  by  the  RBL domain name. By default, Postfix uses the default
       template  as  specified  with   the   default_rbl_reply   configuration
       parameter.  See  there  for  a  discussion  of  the syntax of RBL reply
       templates.

       This feature is available in Postfix 2.0 and later.

readme_directory (default: see postconf -d output)

       The location of Postfix  README  files  that  describe  how  to  build,
       configure or operate a specific Postfix subsystem or feature.

receive_override_options (default: empty)

       Enable  or disable recipient validation, built-in content filtering, or
       address  mapping.  Typically,  these  are  specified  in  master.cf  as
       command-line arguments for the smtpd(8), qmqpd(8) or pickup(8) daemons.

       Specify zero or more of the following options.   The  options  override
       main.cf  settings  and are either implemented by smtpd(8), qmqpd(8), or
       pickup(8) themselves, or they are forwarded to the cleanup server.

       no_unknown_recipient_checks
              Do not try to reject  unknown  recipients  (SMTP  server  only).
              This is typically specified AFTER an external content filter.

       no_address_mappings
              Disable  canonical address mapping, virtual alias map expansion,
              address masquerading,  and  automatic  BCC  (blind  carbon-copy)
              recipients.  This  is  typically  specified  BEFORE  an external
              content filter.

       no_header_body_checks
              Disable header/body_checks. This is typically specified AFTER an
              external content filter.

       Note: when the "BEFORE content filter" receive_override_options setting
       is specified in the main.cf file, specify the  "AFTER  content  filter"
       receive_override_options setting in master.cf (and vice versa).

       Examples:

       receive_override_options =
           no_unknown_recipient_checks, no_header_body_checks
       receive_override_options = no_address_mappings

       This feature is available in Postfix 2.1 and later.

recipient_bcc_maps (default: empty)

       Optional  BCC  (blind  carbon-copy)  address  lookup tables, indexed by
       recipient  address.   The  BCC  address  (multiple  results   are   not
       supported) is added when mail enters from outside of Postfix.

       This feature is available in Postfix 2.1 and later.

       The table search order is as follows:

       ·      Look  up  the  "user+extension@domain.tld" address including the
              optional address extension.

       ·      Look up  the  "user@domain.tld"  address  without  the  optional
              address extension.

       ·      Look  up  the  "user+extension"  address  local  part  when  the
              recipient    domain    equals     $myorigin,     $mydestination,
              $inet_interfaces or $proxy_interfaces.

       ·      Look  up the "user" address local part when the recipient domain
              equals   $myorigin,    $mydestination,    $inet_interfaces    or
              $proxy_interfaces.

       ·      Look up the "@domain.tld" part.

       Specify  the  types  and  names of databases to use.  After change, run
       "postmap /etc/postfix/recipient_bcc".

       Note: if mail to the BCC address bounces it will  be  returned  to  the
       sender.

       Note:  automatic  BCC  recipients  are  produced only for new mail.  To
       avoid mailer loops, automatic BCC recipients are not generated for mail
       that  Postfix  forwards internally, nor for mail that Postfix generates
       itself.

       Example:

       recipient_bcc_maps = hash:/etc/postfix/recipient_bcc

recipient_canonical_classes (default: envelope_recipient, header_recipient)

       What addresses are subject to recipient_canonical_maps address mapping.
       By  default,  recipient_canonical_maps  address  mapping  is applied to
       envelope recipient addresses, and to header recipient addresses.

       Specify one or more of: envelope_recipient, header_recipient

       This feature is available in Postfix 2.2 and later.

recipient_canonical_maps (default: empty)

       Optional  address  mapping  lookup  tables  for  envelope  and   header
       recipient  addresses.   The  table format and lookups are documented in
       canonical(5).

       Note: $recipient_canonical_maps is processed before $canonical_maps.

       Example:

       recipient_canonical_maps = hash:/etc/postfix/recipient_canonical

recipient_delimiter (default: empty)

       The separator between user names  and  address  extensions  (user+foo).
       See canonical(5), local(8), relocated(5) and virtual(5) for the effects
       this has on aliases, canonical, virtual, relocated and on .forward file
       lookups.   Basically,  the  software  tries  user+foo  and .forward+foo
       before trying user and .forward.

       Example:

       recipient_delimiter = +

reject_code (default: 554)

       The numerical Postfix SMTP server response  code  when  a  remote  SMTP
       client request is rejected by the "reject" restriction.

       Do not change this unless you have a complete understanding of RFC 821.

relay_clientcerts (default: empty)

       The list of remote SMTP client certificates for which the Postfix  SMTP
       server will allow access with the permit_tls_clientcerts feature.  This
       feature  does  not  use  certificate  names,   because   Postfix   list
       manipulation  routines  treat  whitespace  and some other characters as
       special.  Instead we use certificate fingerprints as they are difficult
       to fake but easy to use for lookup.

       Postfix  lookup tables are in the form of (key, value) pairs.  Since we
       only need the key, the value can be chosen freely, e.g.   the  name  of
       the   user   or  host:  D7:04:2F:A7:0B:8C:A5:21:FA:31:77:E1:41:8A:EE:80
       lutzpc.at.home

       Example:

       relay_clientcerts = hash:/etc/postfix/relay_clientcerts

       For more fine-grained control,  use  check_ccert_access  to  select  an
       appropriate     access(5)     policy     for    each    client.     See
       RESTRICTION_CLASS_README.

       This feature is available with Postfix 2.2.

relay_destination_concurrency_limit (default:

       $default_destination_concurrency_limit)
       The  maximal  number of parallel deliveries to the same destination via
       the relay message delivery transport. This limit  is  enforced  by  the
       queue  manager.  The message delivery transport name is the first field
       in the entry in the master.cf file.

       This feature is available in Postfix version 2.0 and later.

relay_destination_recipient_limit (default:

       $default_destination_recipient_limit)
       The  maximal  number  of  recipients per delivery via the relay message
       delivery transport. This limit is enforced by the  queue  manager.  The
       message  delivery transport name is the first field in the entry in the
       master.cf file.

       Setting this  parameter  to  a  value  of  1  changes  the  meaning  of
       relay_destination_concurrency_limit  from  concurrency  per domain into
       concurrency per recipient.

       This feature is available in Postfix version 2.0 and later.

relay_domains (default: $mydestination)

       What destination domains (and  subdomains  thereof)  this  system  will
       relay   mail   to.   Subdomain   matching   is   controlled   with  the
       parent_domain_matches_subdomains parameter. For details about  how  the
       relay_domains   value   is   used,   see   the   description   of   the
       permit_auth_destination and  reject_unauth_destination  SMTP  recipient
       restrictions.

       Domains    that   match   $relay_domains   are   delivered   with   the
       $relay_transport mail delivery transport.  The  SMTP  server  validates
       recipient addresses with $relay_recipient_maps and rejects non-existent
       recipients.  See  also  the  relay  domains  address   class   in   the
       ADDRESS_CLASS_README file.

       Note: Postfix will not automatically forward mail for domains that list
       this  system  as  their  primary   or   backup   MX   host.   See   the
       permit_mx_backup restriction in the postconf(5) manual page.

       Specify  a  list  of  host  or  domain  names, "/file/name" patterns or
       "type:table" lookup tables,  separated  by  commas  and/or  whitespace.
       Continue  long  lines  by  starting  the  next  line with whitespace. A
       "/file/name" pattern is replaced by its contents; a "type:table" lookup
       table is matched when a (parent) domain appears as lookup key.

relay_domains_reject_code (default: 554)

       The  numerical  Postfix SMTP server response code when a client request
       is rejected by the reject_unauth_destination recipient restriction.

       Do not change this unless you have a complete understanding of RFC 821.

relay_recipient_maps (default: empty)

       Optional  lookup  tables  with  all valid addresses in the domains that
       match $relay_domains. Specify @domain as a wild-card for  domains  that
       do  not  have  a  valid recipient list. Technically, tables listed with
       $relay_recipient_maps are used as lists: Postfix needs to know only  if
       a  lookup  string  is found or not, but it does not use the result from
       table lookup.

       If this parameter is non-empty,  then  the  Postfix  SMTP  server  will
       reject mail to unknown relay users. This feature is off by default.

       See  also  the  relay domains address class in the ADDRESS_CLASS_README
       file.

       Example:

       relay_recipient_maps = hash:/etc/postfix/relay_recipients

       This feature is available in Postfix 2.0 and later.

relay_transport (default: relay)

       The default  mail  delivery  transport  and  next-hop  information  for
       domains that match the $relay_domains parameter value. This information
       can be overruled with the transport(5) table.

       Specify a string of the form transport:nexthop, where transport is  the
       name  of  a mail delivery transport defined in master.cf.  The :nexthop
       part is optional.  For more details see the transport(5) manual page.

       See also the relay domains address class  in  the  ADDRESS_CLASS_README
       file.

       This feature is available in Postfix 2.0 and later.

relayhost (default: empty)

       The  default host to send non-local mail to when no entry is matched in
       the optional transport(5) table. When no relayhost is  given,  mail  is
       routed directly to the destination.

       On  an  intranet,  specify  the  organizational  domain  name.  If your
       internal DNS uses no MX records,  specify  the  name  of  the  intranet
       gateway host instead.

       In  the  case  of SMTP, specify a domain name, hostname, hostname:port,
       [hostname]:port,  [hostaddress]   or   [hostaddress]:port.   The   form
       [hostname] turns off MX lookups.

       If  you’re  connected  via  UUCP,  see  the UUCP_README file for useful
       information.

       Examples:

       relayhost = $mydomain
       relayhost = [gateway.my.domain]
       relayhost = uucphost
       relayhost = [an.ip.add.ress]

relocated_maps (default: empty)

       Optional lookup tables  with  new  contact  information  for  users  or
       domains  that  no  longer  exist.   The  table  format  and lookups are
       documented in relocated(5).

       If you use this feature, run "postmap /etc/postfix/relocated" to  build
       the  necessary  DBM  or  DB file after change, then "postfix reload" to
       make the changes visible.

       Examples:

       relocated_maps = dbm:/etc/postfix/relocated
       relocated_maps = hash:/etc/postfix/relocated

remote_header_rewrite_domain (default: empty)

       Don’t rewrite message headers from remote  clients  at  all  when  this
       parameter  is  empty; otherwise, rewrite message headers and append the
       specified    domain    name    to    incomplete     addresses.      The
       local_header_rewrite_clients  parameter  controls  what clients Postfix
       considers local.

       Examples:

       The  safe  setting:  append  "domain.invalid"  to   incomplete   header
       addresses  from  remote SMTP clients, so that those addresses cannot be
       confused with local addresses.

           remote_header_rewrite_domain = domain.invalid

       The default, purist, setting: don’t rewrite headers from remote clients
       at all.

           remote_header_rewrite_domain =

require_home_directory (default: no)

       Whether  or not a local(8) recipient’s home directory must exist before
       mail delivery is attempted. By default this test is disabled.   It  can
       be  useful  for  environments  that import home directories to the mail
       server (NOT RECOMMENDED).

resolve_dequoted_address (default: yes)

       Resolve a recipient address safely instead  of  correctly,  by  looking
       inside quotes.

       By  default,  the  Postfix  address resolver does not quote the address
       localpart as per RFC 822, so that additional @ or  %  or  !   operators
       remain  visible.  This  behavior  is  safe  but  it is also technically
       incorrect.

       If you  specify  "resolve_dequoted_address  =  no",  then  the  Postfix
       resolver will not know about additional @ etc. operators in the address
       localpart. This opens opportunities for obscure mail relay attacks with
       user@domain@domain  addresses  when  Postfix provides backup MX service
       for Sendmail systems.

resolve_null_domain (default: no)

       Resolve an address that ends in the "@" null domain  as  if  the  local
       hostname were specified, instead of rejecting the address as invalid.

       This  feature  is  available in Postfix version 2.1 and later.  Earlier
       versions always resolve the null domain as the local hostname.

       The Postfix SMTP server uses this feature to reject  mail  from  or  to
       addresses  that  end  in  the  "@" null domain, and from addresses that
       rewrite into a form that ends in the "@" null domain.

rewrite_service_name (default: rewrite)

       The name of  the  address  rewriting  service.  This  service  rewrites
       addresses  to  standard  form  and resolves them to a (delivery method,
       next-hop host, recipient) triple.

       This feature is available in Postfix 2.0 and later.

sample_directory (default: /etc/postfix)

       The name of the directory with example Postfix configuration files.

sender_based_routing (default: no)

       This parameter should not be used.

sender_bcc_maps (default: empty)

       Optional BCC (blind carbon-copy)  address  lookup  tables,  indexed  by
       sender  address.   The BCC address (multiple results are not supported)
       is added when mail enters from outside of Postfix.

       This feature is available in Postfix 2.1 and later.

       The table search order is as follows:

       ·      Look up the "user+extension@domain.tld"  address  including  the
              optional address extension.

       ·      Look  up  the  "user@domain.tld"  address  without  the optional
              address extension.

       ·      Look up the "user+extension" address local part when the  sender
              domain  equals  $myorigin,  $mydestination,  $inet_interfaces or
              $proxy_interfaces.

       ·      Look up the "user" address local part  when  the  sender  domain
              equals    $myorigin,    $mydestination,    $inet_interfaces   or
              $proxy_interfaces.

       ·      Look up the "@domain.tld" part.

       Specify the types and names of databases to  use.   After  change,  run
       "postmap /etc/postfix/sender_bcc".

       Note:  if  mail  to  the BCC address bounces it will be returned to the
       sender.

       Note: automatic BCC recipients are produced  only  for  new  mail.   To
       avoid mailer loops, automatic BCC recipients are not generated for mail
       that Postfix forwards internally, nor for mail that  Postfix  generates
       itself.

       Example:

       sender_bcc_maps = hash:/etc/postfix/sender_bcc

sender_canonical_classes (default: envelope_sender, header_sender)

       What  addresses  are  subject to sender_canonical_maps address mapping.
       By  default,  sender_canonical_maps  address  mapping  is  applied   to
       envelope sender addresses, and to header sender addresses.

       Specify one or more of: envelope_sender, header_sender

       This feature is available in Postfix 2.2 and later.

sender_canonical_maps (default: empty)

       Optional  address  mapping lookup tables for envelope and header sender
       addresses.   The  table  format   and   lookups   are   documented   in
       canonical(5).

       Example:  you  want to rewrite the SENDER address "user@ugly.domain" to
       "user@pretty.domain", while still  being  able  to  send  mail  to  the
       RECIPIENT address "user@ugly.domain".

       Note: $sender_canonical_maps is processed before $canonical_maps.

       Example:

       sender_canonical_maps = hash:/etc/postfix/sender_canonical

sendmail_path (default: see postconf -d output)

       A  Sendmail  compatibility  feature  that specifies the location of the
       Postfix sendmail(1) command. This command can be used  to  submit  mail
       into the Postfix queue.

service_throttle_time (default: 60s)

       How  long  the  Postfix  master(8)  waits  before forking a server that
       appears to be malfunctioning.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

setgid_group (default: postdrop)

       The  group  ownership of set-gid Postfix commands and of group-writable
       Postfix directories. When this parameter value is changed you  need  to
       re-run   "postfix  set-permissions"  (with  Postfix  2.0  and  earlier:
       "/etc/postfix/post-install set-permissions".

show_user_unknown_table_name (default: yes)

       Display  the  name  of  the  recipient  table  in  the  "User  unknown"
       responses.   The  extra  detail  makes trouble shooting easier but also
       reveals information that is nobody elses business.

       This feature is available in Postfix 2.0 and later.

showq_service_name (default: showq)

       The name of the showq(8) service.  This  service  produces  mail  queue
       status reports.

       This feature is available in Postfix 2.0 and later.

smtp_always_send_ehlo (default: yes)

       Always send EHLO at the start of an SMTP session.

       With  "smtp_always_send_ehlo  =  no",  Postfix sends EHLO only when the
       word "ESMTP" appears  in  the  server  greeting  banner  (example:  220
       spike.porcupine.org ESMTP Postfix).

smtp_bind_address (default: empty)

       An  optional numerical network address that the SMTP client should bind
       to when making an IPv4 connection.

       This can be specified in the main.cf file for all SMTP clients,  or  it
       can  be  specified  in  the  master.cf  file for a specific client, for
       example:

         /etc/postfix/master.cf:
               smtp ... smtp -o smtp_bind_address=11.22.33.44

       Note 1: when inet_interfaces specifies no more than one  IPv4  address,
       and that address is a non-loopback address, it is automatically used as
       the smtp_bind_address.  This supports virtual IP hosting, but can be  a
       problem on multi-homed firewalls. See the inet_interfaces documentation
       for more detail.

       Note 2: address information may be enclosed inside [], but this form is
       not recommended here.

smtp_bind_address6 (default: empty)

       An  optional numerical network address that the SMTP client should bind
       to when making an IPv6 connection.

       This feature is available in Postfix version 2.2 and later.

       This can be specified in the main.cf file for all SMTP clients,  or  it
       can  be  specified  in  the  master.cf  file for a specific client, for
       example:

         /etc/postfix/master.cf:
               smtp ... smtp -o smtp_bind_address6=1:2:3:4:5:6:7:8

       Note 1: when inet_interfaces specifies no more than one  IPv6  address,
       and that address is a non-loopback address, it is automatically used as
       the smtp_bind_address6.  This supports virtual IP hosting, but can be a
       problem on multi-homed firewalls. See the inet_interfaces documentation
       for more detail.

       Note 2: address information may be enclosed inside [], but this form is
       not recommended here.

smtp_cname_overrides_servername (default: yes)

       Allow  DNS  CNAME  records  to override the servername that the Postfix
       SMTP  client  uses  for  logging,  SASL  password  lookup,  TLS  policy
       decisions,  or TLS certificate verification. The default value (yes) is
       backwards   compatible.   Specify   "no"   to   harden   Postfix    2.2
       smtp_tls_per_site   hostname-based   policies  against  false  hostname
       information in DNS CNAME records.

       This feature is available in Postfix 2.2.9 and later.

smtp_connect_timeout (default: 30s)

       The SMTP client time limit for completing a  TCP  connection,  or  zero
       (use the operating system built-in time limit).

       When  no  connection  can  be made within the deadline, the SMTP client
       tries the next address on the mail exchanger list. Specify 0 to disable
       the  time  limit  (i.e.  use  whatever  timeout  is  implemented by the
       operating system).

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

smtp_connection_cache_destinations (default: empty)

       Permanently   enable   SMTP   connection   caching  for  the  specified
       destinations.  With SMTP connection caching, a connection is not closed
       immediately  after  completion  of  a  mail  transaction.  Instead, the
       connection is kept open  for  up  to  $smtp_connection_cache_time_limit
       seconds.   This  allows  connections to be reused for other deliveries,
       and can improve mail delivery performance.

       Specify a comma or  white  space  separated  list  of  destinations  or
       pseudo-destinations:

       ·      if  mail is sent without a relay host: a domain name (the right-
              hand side of an email address, without the [] around  a  numeric
              IP address),

       ·      if  mail is sent via a relay host: a relay host name (without []
              or non-default TCP port), as specified  in  main.cf  or  in  the
              transport map,

       ·      a  /file/name  with  domain  names  and/or  relay  host names as
              defined above,

       ·      a "type:table" with domain names and/or relay hosts name on  the
              left-hand  side.   The  right-hand side result from "type:table"
              lookups is ignored.

       This feature is available in Postfix 2.2 and later.

smtp_connection_cache_on_demand (default: yes)

       Temporarily enable SMTP connection caching while a  destination  has  a
       high volume of mail in the active queue.  With SMTP connection caching,
       a connection is not closed  immediately  after  completion  of  a  mail
       transaction.    Instead,   the  connection  is  kept  open  for  up  to
       $smtp_connection_cache_time_limit seconds.  This allows connections  to
       be   reused  for  other  deliveries,  and  can  improve  mail  delivery
       performance.

       This feature is available in Postfix 2.2 and later.

smtp_connection_cache_reuse_limit (default: 10)

       When SMTP connection caching is enabled, the number of  times  that  an
       SMTP session is reused before it is closed.

       This feature is available in Postfix 2.2 and later.

smtp_connection_cache_time_limit (default: 2s)

       When  SMTP  connection  caching  is enabled, the amount of time that an
       unused SMTP client socket is kept open before it  is  closed.   Do  not
       specify larger values without permission from the remote sites.

       This feature is available in Postfix 2.2 and later.

smtp_data_done_timeout (default: 600s)

       The  SMTP client time limit for sending the SMTP ".", and for receiving
       the server response.

       When no response is received within the deadline, a warning  is  logged
       that the mail may be delivered multiple times.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

smtp_data_init_timeout (default: 120s)

       The SMTP client time limit for sending the SMTP DATA command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

smtp_data_xfer_timeout (default: 180s)

       The SMTP client time limit for sending the SMTP message content.   When
       the  connection makes no progress for more than $smtp_data_xfer_timeout
       seconds the SMTP client terminates the transfer.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

smtp_defer_if_no_mx_address_found (default: no)

       Defer mail delivery when no MX record resolves to an IP address.

       The  default  (no)  is  to return the mail as undeliverable. With older
       Postfix versions the default was to keep trying  to  deliver  the  mail
       until someone fixed the MX record or until the mail was too old.

       Note:  Postfix always ignores MX records with equal or worse preference
       than the local MTA itself.

       This feature is available in Postfix 2.1 and later.

smtp_destination_concurrency_limit (default:

       $default_destination_concurrency_limit)
       The  maximal  number of parallel deliveries to the same destination via
       the smtp message delivery transport. This  limit  is  enforced  by  the
       queue  manager.  The message delivery transport name is the first field
       in the entry in the master.cf file.

smtp_destination_recipient_limit (default:

       $default_destination_recipient_limit)
       The  maximal  number  of  recipients  per delivery via the smtp message
       delivery transport. This limit is enforced by the  queue  manager.  The
       message  delivery transport name is the first field in the entry in the
       master.cf file.

       Setting this  parameter  to  a  value  of  1  changes  the  meaning  of
       smtp_destination_concurrency_limit  from  concurrency  per  domain into
       concurrency per recipient.

smtp_discard_ehlo_keyword_address_maps (default: empty)

       Lookup tables, indexed by the remote SMTP  server  address,  with  case
       insensitive  lists  of EHLO keywords (pipelining, starttls, auth, etc.)
       that the SMTP client will ignore in the EHLO  response  from  a  remote
       SMTP server. See smtp_discard_ehlo_keywords for details.

smtp_discard_ehlo_keywords (default: empty)

       A  case  insensitive list of EHLO keywords (pipelining, starttls, auth,
       etc.) that the SMTP client will ignore in  the  EHLO  response  from  a
       remote SMTP server.

       Notes:

       ·      Specify the silent-discard pseudo keyword to prevent this action
              from being logged.

       ·      Use  the   smtp_discard_ehlo_keyword_address_maps   feature   to
              discard EHLO keywords selectively.

smtp_enforce_tls (default: no)

       Enforcement  mode: require that remote SMTP servers use TLS encryption,
       and never send mail in the clear.  This also requires that  the  remote
       SMTP  server  hostname  matches  the  information  in the remote server
       certificate, and that the remote SMTP server certificate was issued  by
       a  CA  that  is  trusted by the Postfix SMTP client. If the certificate
       doesn’t verify or the hostname doesn’t match, delivery is deferred  and
       mail stays in the queue.

       The  server  hostname is matched against all names provided as dNSNames
       in the SubjectAlternativeName.   If  no  dNSNames  are  specified,  the
       CommonName   is   checked.   The  behavior  may  be  changed  with  the
       smtp_tls_enforce_peername option.

       This option is useful only if you are definitely  sure  that  you  will
       only  connect to servers that support RFC 2487 _and_ that provide valid
       server certificates.  Typical use is for clients that  send  all  their
       email to a dedicated mailhub.

smtp_generic_maps (default: empty)

       Optional  lookup  tables  that  perform  address  rewriting in the SMTP
       client, typically to transform a locally valid address into a  globally
       valid  address  when  sending mail across the Internet.  This is needed
       when the local machine does not have its own Internet domain name,  but
       uses something like localdomain.local instead.

       The table format and lookups are documented in generic(5); examples are
       shown in the ADDRESS_REWRITING_README and STANDARD_CONFIGURATION_README
       documents.

       This feature is available in Postfix 2.2 and later.

smtp_helo_name (default: $myhostname)

       The hostname to send in the SMTP EHLO or HELO command.

       The  default  value  is  the  machine  hostname.  Specify a hostname or
       [ip.add.re.ss].

       This information can be specified in the  main.cf  file  for  all  SMTP
       clients,  or  it  can be specified in the master.cf file for a specific
       client, for example:

         /etc/postfix/master.cf:
               mysmtp ... smtp -o smtp_helo_name=foo.bar.com

       This feature is available in Postfix 2.0 and later.

smtp_helo_timeout (default: 300s)

       The SMTP client time limit for sending the HELO or  EHLO  command,  and
       for receiving the initial server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

smtp_host_lookup (default: dns)

       What mechanisms when the SMTP client  uses  to  look  up  a  host’s  IP
       address.  This parameter is ignored when DNS lookups are disabled.

       Specify one of the following:

       dns    Hosts can be found in the DNS (preferred).

       native Use the native naming service only (nsswitch.conf, or equivalent
              mechanism).

       dns, native
              Use the native service for hosts not found in the DNS.

       This feature is available in Postfix 2.1 and later.

smtp_line_length_limit (default: 990)

       The maximal length of message header and body lines that  Postfix  will
       send via SMTP.  Longer lines are broken by inserting "<CR><LF><SPACE>".
       This minimizes the damage to MIME formatted mail.

       By default, the line length is limited to 990 characters, because  some
       server implementations cannot receive mail with long lines.

smtp_mail_timeout (default: 300s)

       The  SMTP  client time limit for sending the MAIL FROM command, and for
       receiving the server response.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

smtp_mx_address_limit (default: 0)

       The  maximal number of MX (mail exchanger) IP addresses that can result
       from mail exchanger lookups, or zero (no limit).

       This feature is available in Postfix 2.1 and later.

smtp_mx_session_limit (default: 2)

       The maximal number of SMTP sessions per delivery request before  giving
       up  or  delivering  to a fall-back relay host, or zero (no limit). This
       restriction ignores IP addresses that fail to complete the SMTP initial
       handshake.

       This feature is available in Postfix 2.1 and later.

smtp_never_send_ehlo (default: no)

       Never  send  EHLO  at  the  start  of  an  SMTP  session.  See also the
       smtp_always_send_ehlo parameter.

smtp_pix_workaround_delay_time (default: 10s)

       How long the Postfix SMTP client pauses before sending  ".<CR><LF>"  in
       order to work around the PIX firewall "<CR><LF>.<CR><LF>" bug.

       Choosing  a  too  short  time  makes  this  workaround ineffective when
       sending large messages over slow network connections.

smtp_pix_workaround_threshold_time (default: 500s)

       How  long  a  message  must  be  queued   before   the   PIX   firewall
       "<CR><LF>.<CR><LF>" bug workaround is turned on.

       By  default,  the  workaround is turned off for mail that is queued for
       less than 500 seconds. In  other  words,  the  workaround  is  normally
       turned off for the first delivery attempt.

       Specify 0 to enable the PIX firewall "<CR><LF>.<CR><LF>" bug workaround
       upon the first delivery attempt.

smtp_quit_timeout (default: 300s)

       The SMTP client time limit  for  sending  the  QUIT  command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

smtp_quote_rfc821_envelope (default: yes)

       Quote addresses in SMTP MAIL FROM and RCPT TO commands as  required  by
       RFC  821. This includes putting quotes around an address localpart that
       ends in ".".

       The default is to comply with RFC 821. If you have to send  mail  to  a
       broken SMTP server, configure a special SMTP client in master.cf:

           /etc/postfix/master.cf:
               broken-smtp . . . smtp -o smtp_quote_rfc821_envelope=no

       and  route  mail  for  the destination in question to the "broken-smtp"
       message delivery with a transport(5) table.

       This feature is available in Postfix 2.1 and later.

smtp_randomize_addresses (default: yes)

       Randomize the order of equal-preference MX host addresses.  This  is  a
       performance feature of the Postfix SMTP client.

smtp_rcpt_timeout (default: 300s)

       The  SMTP  client  time limit for sending the SMTP RCPT TO command, and
       for receiving the server response.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

smtp_rset_timeout (default: 20s)

       The  SMTP  client  time  limit  for  sending  the RSET command, and for
       receiving the server response. The SMTP client sends RSET in  order  to
       finish a recipient address probe, or to verify that a cached session is
       still usable.

       This feature is available in Postfix 2.1 and later.

smtp_sasl_auth_enable (default: no)

       Enable SASL authentication in the Postfix SMTP client.  By default, the
       Postfix SMTP client uses no authentication.

       Example:

       smtp_sasl_auth_enable = yes

smtp_sasl_mechanism_filter (default: empty)

       If non-empty, a Postfix SMTP client filter for the remote SMTP server’s
       list  of  offered  SASL  mechanisms.   Different  client   and   server
       implementations  may support different mechanism lists. By default, the
       Postfix  SMTP  client  will  use   the   intersection   of   the   two.
       smtp_sasl_mechanism_filter further restricts what server mechanisms the
       client will take into consideration.

       Specify mechanism names, "/file/name" patterns or  "type:table"  lookup
       tables.  The  right-hand  side  result  from  "type:table"  lookups  is
       ignored.

       This feature is available in Postfix 2.2 and later.

       Examples:

       smtp_sasl_mechanism_filter = plain, login
       smtp_sasl_mechanism_filter = /etc/postfix/smtp_mechs
       smtp_sasl_mechanism_filter = !gssapi, !login, static:rest

smtp_sasl_password_maps (default: empty)

       Optional SMTP client lookup tables with one username:password entry per
       remote  hostname  or  domain.   If  a  remote  host  or  domain  has no
       username:password entry, then the Postfix SMTP client will not  attempt
       to authenticate to the remote host.

       The  Postfix  SMTP client opens the lookup table before going to chroot
       jail, so you can leave the password file in /etc/postfix.

smtp_sasl_security_options (default: noplaintext, noanonymous)

       What authentication mechanisms the Postfix SMTP client  is  allowed  to
       use.   The  list  of  available  authentication  mechanisms  is  system
       dependent.

       Specify zero or more of the following:

       noplaintext
              Disallow methods that use plaintext passwords.

       noactive
              Disallow methods subject to active (non-dictionary) attack.

       nodictionary
              Disallow methods subject to passive (dictionary) attack.

       noanonymous
              Disallow methods that allow anonymous authentication.

       mutual_auth
              Only allow  methods  that  provide  mutual  authentication  (not
              available with SASL version 1).

       Example:

       smtp_sasl_security_options = noplaintext

smtp_sasl_tls_security_options (default: $smtp_sasl_security_options)

       The  SASL  authentication security options that the Postfix SMTP client
       uses for TLS encrypted SMTP sessions.

smtp_send_xforward_command (default: no)

       Send the non-standard XFORWARD command when  the  Postfix  SMTP  server
       EHLO response announces XFORWARD support.

       This  allows  an  "smtp" delivery agent, used for injecting mail into a
       content filter, to forward the name, address, protocol and HELO name of
       the  original  client to the content filter and downstream queuing SMTP
       server. This can produce more useful logging than  localhost[127.0.0.1]
       etc.

       This feature is available in Postfix 2.1 and later.

smtp_skip_4xx_greeting (default: yes)

       Skip SMTP servers that greet with a 4XX status code (go away, try again
       later).

       By  default,  Postfix  moves  on  the  next  mail  exchanger.   Specify
       "smtp_skip_4xx_greeting   =   no"  if  Postfix  should  defer  delivery
       immediately.

       This feature is available in Postfix version 2.0  and  earlier.   Later
       Postfix  versions always skip SMTP servers that greet with a 4XX status
       code.

smtp_skip_5xx_greeting (default: yes)

       Skip SMTP servers that greet with a 5XX status code (go  away,  do  not
       try again later).

       By  default,  the Postfix SMTP client moves on the next mail exchanger.
       Specify "smtp_skip_5xx_greeting = no" if Postfix should bounce the mail
       immediately.  The default setting is incorrect, but it is what a lot of
       people expect to happen.

smtp_skip_quit_response (default: yes)

       Do not wait for the response to the SMTP QUIT command.

smtp_starttls_timeout (default: 300s)

       Time limit for Postfix SMTP client write and read operations during TLS
       startup and shutdown handshake procedures.

smtp_tls_CAfile (default: empty)

       The  file with the certificate of the certification authority (CA) that
       issued the Postfix SMTP client certificate.  This is needed  only  when
       the  CA  certificate  is  not already present in the client certificate
       file.

       Example:

       smtp_tls_CAfile = /etc/postfix/CAcert.pem

smtp_tls_CApath (default: empty)

       Directory with PEM format certificate authority certificates  that  the
       Postfix  SMTP  client  uses to verify a remote SMTP server certificate.
       Don’t forget to create the necessary "hash" links  with,  for  example,
       "$OPENSSL_HOME/bin/c_rehash /etc/postfix/certs".

       To  use  this option in chroot mode, this directory (or a copy) must be
       inside the chroot jail.

       Example:

       smtp_tls_CApath = /etc/postfix/certs

smtp_tls_cert_file (default: empty)

       File with the Postfix SMTP client RSA certificate in PEM format.   This
       file may also contain the client private key, and these may be the same
       as the server certificate and key file.

       In order to verify certificates, the  CA  certificate  (in  case  of  a
       certificate  chain, all CA certificates) must be available.  You should
       add  these  certificates  to  the  server   certificate,   the   server
       certificate first, then the issuing CA(s).

       Example:   the   certificate   for   "client.dom.ain"   was  issued  by
       "intermediate CA" which itself has a certificate of "root CA".   Create
       the  client.pem  file  with  "cat  client_cert.pem  intermediate_CA.pem
       root_CA.pem > client.pem".

       If you want to accept remote SMTP server certificates issued  by  these
       CAs   yourself,   you   can   also  add  the  CA  certificates  to  the
       smtp_tls_CAfile, in which case it is not necessary to have them in  the
       smtp_tls_cert_file or smtp_tls_dcert_file.

       A  certificate  supplied  here must be usable as SSL client certificate
       and hence pass the "openssl verify -purpose sslclient ..." test.

       Example:

       smtp_tls_cert_file = /etc/postfix/client.pem

smtp_tls_cipherlist (default: empty)

       Controls the Postfix SMTP client  TLS  cipher  selection  scheme.   For
       details,  see  the  OpenSSL  documentation.  Note: do not use "" quotes
       around the parameter value.

smtp_tls_dcert_file (default: empty)

       File with the Postfix SMTP client DSA certificate in PEM format.   This
       file may also contain the server private key.

       See the discussion under smtp_tls_cert_file for more details.

       Example:

       smtp_tls_dcert_file = /etc/postfix/client-dsa.pem

smtp_tls_dkey_file (default: $smtp_tls_dcert_file)

       File  with  the Postfix SMTP client DSA private key in PEM format.  The
       private key must not be encrypted. In other  words,  the  key  must  be
       accessible without password.

       This  file  may  be combined with the server certificate file specified
       with $smtp_tls_cert_file.

smtp_tls_enforce_peername (default: yes)

       When TLS encryption is enforced, require that the  remote  SMTP  server
       hostname matches the information in the remote SMTP server certificate.
       As of RFC 2487 the requirements for hostname checking for  MTA  clients
       are not specified.

       This  option  can  be set to "no" to disable strict peer name checking.
       This setting has no effect on sessions  that  are  controlled  via  the
       smtp_tls_per_site table.

       Disabling   the   hostname   verification  can  make  sense  in  closed
       environment where special CAs are created.  If not used carefully, this
       option opens the danger of a "man-in-the-middle" attack (the CommonName
       of this attacker will be logged).

smtp_tls_key_file (default: $smtp_tls_cert_file)

       File with the Postfix SMTP client RSA private key in PEM format.   This
       file  may  be  combined with the client certificate file specified with
       $smtp_tls_cert_file.

       The private key must not be encrypted. In other words, the key must  be
       accessible without password.

       Example:

       smtp_tls_key_file = $smtp_tls_cert_file

smtp_tls_loglevel (default: 0)

       Enable  additional  Postfix  SMTP client logging of TLS activity.  Each
       logging level also includes the information that is logged at  a  lower
       logging level.

              0 Disable logging of TLS activity.

              1 Log TLS handshake and certificate information.

              2 Log levels during TLS negotiation.

              3 Log hexadecimal and ASCII dump of TLS negotiation process.

              4  Log hexadecimal and ASCII dump of complete transmission after
              STARTTLS.

       Use "smtp_tls_loglevel = 3" only in case of problems. Use of loglevel 4
       is strongly discouraged.

smtp_tls_note_starttls_offer (default: no)

       Log the hostname of a remote SMTP server that offers STARTTLS, when TLS
       is not already enabled for that server.

       The logfile record looks like:

       postfix/smtp[pid]:  Host offered STARTTLS: [name.of.host]

smtp_tls_per_site (default: empty)

       Optional lookup tables with the Postfix SMTP client TLS usage policy by
       next-hop  destination  and  by  remote SMTP server hostname.  When both
       lookups succeed, the more specific per-site policy  (NONE,  MUST,  etc)
       overrides  the  less  specific  one (MAY), and the more secure per-site
       policy (MUST, etc) overrides the less secure one (NONE).

       Specify a next-hop destination or  server  hostname  on  the  left-hand
       side;  no wildcards are allowed. The next-hop destination is either the
       recipient domain, or the  destination  specified  with  a  transport(5)
       table,  the  relayhost parameter, or the relay_transport parameter.  On
       the right hand side specify one of the following keywords:

       NONE   Don’t use TLS at all. This overrides a less specific MAY  lookup
              result  from  the  alternate  host  or  next-hop lookup key, and
              overrides  the  global   smtp_use_tls,   smtp_enforce_tls,   and
              smtp_tls_enforce_peername settings.

       MAY    Try  to  use  TLS if the server announces support, otherwise use
              the unencrypted connection. This has less precedence than a more
              specific  result  (including  NONE)  from  the alternate host or
              next-hop lookup key, and  has  less  precedence  than  the  more
              specific      global     "smtp_enforce_tls     =     yes"     or
              "smtp_tls_enforce_peername = yes".

       MUST_NOPEERMATCH
              Require TLS encryption, but do not require that the remote  SMTP
              server  hostname  matches  the  information  in  the remote SMTP
              server certificate, or that the server certificate was issued by
              a  trusted  CA.  This  overrides  a  less  secure NONE or a less
              specific MAY lookup result from the alternate host  or  next-hop
              lookup    key,    and   overrides   the   global   smtp_use_tls,
              smtp_enforce_tls and smtp_tls_enforce_peername settings.

       MUST   Require TLS encryption, require  that  the  remote  SMTP  server
              hostname  matches  the  information  in  the  remote SMTP server
              certificate, and require that the remote SMTP server certificate
              was  issued  by  a trusted CA. This overrides a less secure NONE
              and MUST_NOPEERMATCH or a less specific MAY lookup  result  from
              the  alternate  host  or  next-hop lookup key, and overrides the
              global        smtp_use_tls,         smtp_enforce_tls         and
              smtp_tls_enforce_peername settings.

       As long as no secure DNS lookup mechanism is available, false hostnames
       in MX or CNAME responses can change the server  hostname  that  Postfix
       uses  for  TLS  policy lookup and server certificate verification. Even
       with a perfect  match  between  the  server  hostname  and  the  server
       certificate,  there  is  no  guarantee that Postfix is connected to the
       right server.  To avoid this loophole take the following steps:

       ·      Disallow  CNAME   hostname   overrides.   In   main.cf   specify
              "smtp_cname_overrides_servername  =  no".  This  prevents  false
              hostname information in DNS  CNAME  records  from  changing  the
              server  hostname  that  Postfix  uses  for TLS policy lookup and
              server certificate verification. This feature  requires  Postfix
              2.2.9 or later.

       ·      Eliminate  MX  lookups. Specify local transport(5) table entries
              for  sensitive  domains   with   explicit   smtp:[mailhost]   or
              smtp:[mailhost]:port destinations.  This prevents false hostname
              information in DNS MX records from changing the server  hostname
              that  Postfix  uses for TLS policy lookup and server certificate
              verification.

       ·      Specify MUST for these mail hosts (including [ ]  and  port)  in
              the smtp_tls_per_site table.

smtp_tls_scert_verifydepth (default: 5)

       The  verification depth for remote SMTP server certificates. A depth of
       1 is sufficient, if the certificate is directly issued by a  CA  listed
       in  the  CA  files.   The  default  value (5) should suffice for longer
       chains (the root CA issues special CA  which  then  issues  the  actual
       certificate...).

smtp_tls_session_cache_database (default: empty)

       Name  of  the  file  containing  the  optional  Postfix SMTP client TLS
       session cache. Specify a database type that supports enumeration,  such
       as  btree  or sdbm; there is no need to support concurrent access.  The
       file is created if it does not exist.

       Note: dbm databases are not  suitable.  TLS  session  objects  are  too
       large.

       Example:

       smtp_tls_session_cache_database = btree:/var/postfix/smtp_scache

smtp_tls_session_cache_timeout (default: 3600s)

       The   expiration   time  of  Postfix  SMTP  client  TLS  session  cache
       information.   A  cache  cleanup  is   performed   periodically   every
       $smtp_tls_session_cache_timeout seconds.

smtp_use_tls (default: no)

       Opportunistic  mode:  use  TLS  when  a  remote  SMTP  server announces
       STARTTLS support, otherwise send the mail in the  clear.  Beware:  some
       SMTP  servers  offer STARTTLS even if it is not configured.  If the TLS
       handshake fails, and no other server is available, delivery is deferred
       and  mail  stays  in  the queue.  If this is a concern for you, use the
       smtp_tls_per_site feature instead.

smtp_xforward_timeout (default: 300s)

       The SMTP client time limit for sending the XFORWARD  command,  and  for
       receiving the server response.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

       This feature is available in Postfix 2.1 and later.

smtpd_authorized_verp_clients (default: $authorized_verp_clients)

       What SMTP clients are allowed  to  specify  the  XVERP  command.   This
       command  requests that mail be delivered one recipient at a time with a
       per recipient return address.

       By default, no clients are allowed to specify XVERP.

       This parameter was renamed with  Postfix  2.1.  The  default  value  is
       backwards compatible with Postfix 2.0.

       Specify  a list of network/netmask patterns, separated by commas and/or
       whitespace. The mask specifies the number of bits in the  network  part
       of a host address. You can also specify hostnames or .domain names (the
       initial  dot  causes  the  domain  to  match  any   name   below   it),
       "/file/name"  or  "type:table"  patterns.   A  "/file/name"  pattern is
       replaced by its contents; a "type:table" lookup table is matched when a
       table  entry  matches  a  lookup string (the lookup result is ignored).
       Continue long lines by starting the next line with whitespace.

       Note: IP version 6 address information must be specified inside  []  in
       the  smtpd_authorized_verp_clients  value,  and in files specified with
       "/file/name".  IP version 6 addresses contain the  ":"  character,  and
       would otherwise be confused with a "type:table" pattern.

smtpd_authorized_xclient_hosts (default: empty)

       What SMTP clients are allowed to use the XCLIENT feature.  This command
       overrides SMTP client information that  is  used  for  access  control.
       Typical use is for SMTP-based content filters, fetchmail-like programs,
       or SMTP server access rule testing. See the XCLIENT_README document for
       details.

       This feature is available in Postfix 2.1 and later.

       By default, no clients are allowed to specify XCLIENT.

       Specify  a list of network/netmask patterns, separated by commas and/or
       whitespace. The mask specifies the number of bits in the  network  part
       of a host address. You can also specify hostnames or .domain names (the
       initial  dot  causes  the  domain  to  match  any   name   below   it),
       "/file/name"  or  "type:table"  patterns.   A  "/file/name"  pattern is
       replaced by its contents; a "type:table" lookup table is matched when a
       table  entry  matches  a  lookup string (the lookup result is ignored).
       Continue long lines by starting the next line with whitespace.

       Note: IP version 6 address information must be specified inside  []  in
       the  smtpd_authorized_xclient_hosts  value, and in files specified with
       "/file/name".  IP version 6 addresses contain the  ":"  character,  and
       would otherwise be confused with a "type:table" pattern.

smtpd_authorized_xforward_hosts (default: empty)

       What  SMTP  clients  are  allowed  to  use  the XFORWARD feature.  This
       command forwards information that is  used  to  improve  logging  after
       SMTP-based  content  filters.  See  the  XFORWARD_README  document  for
       details.

       This feature is available in Postfix 2.1 and later.

       By default, no clients are allowed to specify XFORWARD.

       Specify a list of network/netmask patterns, separated by commas  and/or
       whitespace.  The  mask specifies the number of bits in the network part
       of a host address. You can also specify hostnames or .domain names (the
       initial   dot   causes   the  domain  to  match  any  name  below  it),
       "/file/name" or  "type:table"  patterns.   A  "/file/name"  pattern  is
       replaced by its contents; a "type:table" lookup table is matched when a
       table entry matches a lookup string (the  lookup  result  is  ignored).
       Continue long lines by starting the next line with whitespace.

       Note:  IP  version 6 address information must be specified inside [] in
       the smtpd_authorized_xforward_hosts value, and in files specified  with
       "/file/name".   IP  version  6 addresses contain the ":" character, and
       would otherwise be confused with a "type:table" pattern.

smtpd_banner (default: $myhostname ESMTP $mail_name)

       The text that follows the 220 status code in the SMTP greeting  banner.
       Some  people  like  to  see  the  mail  version advertised. By default,
       Postfix shows no version.

       You MUST specify $myhostname at the start of the text. This is required
       by the SMTP protocol.

       Example:

       smtpd_banner = $myhostname ESMTP $mail_name ($mail_version)

smtpd_client_connection_count_limit (default: 50)

       How many simultaneous connections any client is allowed to make to this
       service.  By default, the limit is set  to  half  the  default  process
       limit value.

       To disable this feature, specify a limit of 0.

       WARNING:  The purpose of this feature is to limit abuse. It must not be
       used to regulate legitimate mail traffic.

       This feature is available in Postfix 2.2 and later.

smtpd_client_connection_rate_limit (default: 0)

       The maximal number of connection attempts any client is allowed to make
       to  this  service  per  time unit.  The time unit is specified with the
       anvil_rate_time_unit configuration parameter.

       By default, a client can make as many  connections  per  time  unit  as
       Postfix can accept.

       To disable this feature, specify a limit of 0.

       WARNING:  The purpose of this feature is to limit abuse. It must not be
       used to regulate legitimate mail traffic.

       This feature is available in Postfix 2.2 and later.

       Example:

       smtpd_client_connection_rate_limit = 1000

smtpd_client_event_limit_exceptions (default: $mynetworks)

       Clients that are excluded from connection count,  connection  rate,  or
       SMTP request rate restrictions.

       By default, clients in trusted networks are excluded. Specify a list of
       network blocks, hostnames or .domain names (the initial dot causes  the
       domain to match any name below it).

       Note:  IP  version 6 address information must be specified inside [] in
       the smtpd_client_event_limit_exceptions value, and in  files  specified
       with  "/file/name".   IP version 6 addresses contain the ":" character,
       and would otherwise be confused with a "type:table" pattern.

       This feature is available in Postfix 2.2 and later.

smtpd_client_message_rate_limit (default: 0)

       The maximal number of message delivery  requests  that  any  client  is
       allowed to make to this service per time unit, regardless of whether or
       not  Postfix  actually  accepts  those  messages.   The  time  unit  is
       specified with the anvil_rate_time_unit configuration parameter.

       By  default,  a  client  can send as many message delivery requests per
       time unit as Postfix can accept.

       To disable this feature, specify a limit of 0.

       WARNING: The purpose of this feature is to limit abuse. It must not  be
       used to regulate legitimate mail traffic.

       This feature is available in Postfix 2.2 and later.

       Example:

       smtpd_client_message_rate_limit = 1000

smtpd_client_recipient_rate_limit (default: 0)

       The maximal number of recipient addresses that any client is allowed to
       send to this service per  time  unit,  regardless  of  whether  or  not
       Postfix  actually accepts those recipients.  The time unit is specified
       with the anvil_rate_time_unit configuration parameter.

       By default, a client can make as many recipient addresses per time unit
       as Postfix can accept.

       To disable this feature, specify a limit of 0.

       WARNING:  The purpose of this feature is to limit abuse. It must not be
       used to regulate legitimate mail traffic.

       This feature is available in Postfix 2.2 and later.

       Example:

       smtpd_client_recipient_rate_limit = 1000

smtpd_client_restrictions (default: empty)

       Optional SMTP server access restrictions in the  context  of  a  client
       SMTP connection request.

       The default is to allow all connection requests.

       Specify  a list of restrictions, separated by commas and/or whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions   are  applied  in  the  order  as  specified;  the  first
       restriction that matches wins.

       The following restrictions are specific to client  hostname  or  client
       network address information.

       check_ccert_access type:table
              When   the   remote   SMTP   client   certificate   is  verified
              successfully, use the client certificate fingerprint  as  lookup
              key  for  the  specified  access(5)  database.  This  feature is
              available with Postfix 2.2.

       check_client_access type:table
              Search the specified access database for  the  client  hostname,
              parent  domains,  client  IP  address,  or  networks obtained by
              stripping least significant octets.  See  the  access(5)  manual
              page for details.

       permit_inet_interfaces
              Permit   the   request   when  the  client  IP  address  matches
              $inet_interfaces.

       permit_mynetworks
              Permit the request  when  the  client  IP  address  matches  any
              network or network address listed in  $mynetworks.

       permit_sasl_authenticated
              Permit the request when the client is successfully authenticated
              via the RFC 2554 (AUTH) protocol.

       permit_tls_all_clientcerts
              Permit the request when the remote SMTP  client  certificate  is
              verified  successfully.   This  option  must  be  used only if a
              special CA issues the certificates and only this CA is listed as
              trusted  CA, otherwise all clients with a recognized certificate
              would be allowed  to  relay.  This  feature  is  available  with
              Postfix 2.2.

       permit_tls_clientcerts
              Permit  the  request  when the remote SMTP client certificate is
              verified successfully, and the certificate fingerprint is listed
              in  $relay_clientcerts.  This  feature is available with Postfix
              2.2.

       reject_rbl_client rbl_domain=d.d.d.d
              Reject the request when the reversed client network  address  is
              listed  with  the  A  record "d.d.d.d" under rbl_domain (Postfix
              version 2.1 and later only).  If  no  "=d.d.d.d"  is  specified,
              reject  the  request when the reversed client network address is
              listed with any A record under rbl_domain.
              The maps_rbl_reject_code parameter specifies the  response  code
              for  rejected  requests  (default:   554), the default_rbl_reply
              parameter  specifies  the  default   server   reply,   and   the
              rbl_reply_maps   parameter  specifies tables with server replies
              indexed by rbl_domain.  This feature is available in Postfix 2.0
              and later.

       reject_rhsbl_client rbl_domain=d.d.d.d
              Reject the request when the client hostname is listed with the A
              record "d.d.d.d" under rbl_domain (Postfix version 2.1 and later
              only).   If  no "=d.d.d.d" is specified, reject the request when
              the reversed client network address is listed with any A  record
              under  rbl_domain.  See  the reject_rbl_client description above
              for  additional  RBL  related  configuration  parameters.   This
              feature is available in Postfix 2.0 and later.

       reject_unknown_client
              Reject  the  request  when  the  client  IP  address  has no PTR
              (address to name) record in the DNS, or when the PTR record does
              not have a matching A (name to address) record.
              The  unknown_client_reject_code parameter specifies the response
              code for rejected requests (default: 450). The reply  is  always
              450  in  case  the  hostname  lookup  failed  due to a temporary
              problem.

       In addition, you can use any of  the  following  generic  restrictions.
       These restrictions are applicable in any SMTP command context.

       check_policy_service servername
              Query  the  specified policy server. See the SMTPD_POLICY_README
              document for details. This feature is available in  Postfix  2.1
              and later.

       defer  Defer  the  request. The client is told to try again later. This
              restriction is useful at the end of a restriction list, to  make
              the default policy explicit.
              The  defer_code  parameter  specifies the SMTP server reply code
              (default: 450).

       defer_if_permit
              Defer the request if some later restriction would result  in  an
              explicit  or  implicit  PERMIT  action.   This  is useful when a
              blacklisting feature fails due to  a  temporary  problem.   This
              feature is available in Postfix 2.1 and later.

       defer_if_reject
              Defer  the  request  if some later restriction would result in a
              REJECT action.  This is useful when a whitelisting feature fails
              due  to  a  temporary  problem.   This  feature  is available in
              Postfix 2.1 and later.

       permit Permit the request. This restriction is useful at the end  of  a
              restriction list, to make the default policy explicit.

       reject_multi_recipient_bounce
              Reject the request when the envelope sender is the null address,
              and the message has multiple envelope recipients. Although  this
              usage  is  technically  allowed,  it seems to have no legitimate
              application.
              Note: this restriction can  only  work  reliably  when  used  in
              smtpd_data_restrictions    or    smtpd_end_of_data_restrictions,
              because the total number  of  recipients  is  not  known  at  an
              earlier  stage  of the SMTP conversation.  Use at the RCPT stage
              will only reject the second etc.  recipient.
              The multi_recipient_bounce_reject_code parameter  specifies  the
              response  code  for  rejected  requests  (default:   550).  This
              feature is available in Postfix 2.1 and later.

       reject_unauth_pipelining
              Reject the request when the client sends SMTP commands ahead  of
              time  where  it  is  not  allowed, or when the client sends SMTP
              commands ahead of time without  knowing  that  Postfix  actually
              supports  ESMTP  command  pipelining.  This stops mail from bulk
              mail software that improperly uses ESMTP command  pipelining  in
              order to speed up deliveries.
              Note:    reject_unauth_pipelining    is   not   useful   outside
              smtpd_data_restrictions when 1)  the  client  uses  ESMTP  (EHLO
              instead  of  HELO)  and  2) with "smtpd_delay_reject = yes" (the
              default).  The use  of  reject_unauth_pipelining  in  the  other
              restriction contexts is therefore not recommended.

       reject Reject  the  request. This restriction is useful at the end of a
              restriction list, to make  the  default  policy  explicit.   The
              reject_code  configuration parameter specifies the response code
              to rejected requests (default: 554).

       sleep seconds
              Pause for the specified number of seconds and proceed  with  the
              next  restriction in the list, if any. This may stop zombie mail
              when used as:

       /etc/postfix/main.cf:
           smtpd_client_restrictions =
               sleep 1, reject_unauth_pipelining
           smtpd_delay_reject = no
       This feature is available in Postfix 2.3.

       warn_if_reject
              Change the meaning of the next restriction, so that  it  logs  a
              warning instead of rejecting a request (look for logfile records
              that contain "reject_warning"). This is useful for  testing  new
              restrictions in a "live" environment without risking unnecessary
              loss of mail.

       Other restrictions that are valid in this context:

       ·      SMTP command specific restrictions that are described under  the
              smtpd_helo_restrictions,       smtpd_sender_restrictions      or
              smtpd_recipient_restrictions parameters. When  helo,  sender  or
              recipient        restrictions       are       listed       under
              smtpd_client_restrictions,   they   have   effect   only    with
              "smtpd_delay_reject  =  yes", so that $smtpd_client_restrictions
              is evaluated at the time of the RCPT TO command.

       Example:

       smtpd_client_restrictions = permit_mynetworks, reject_unknown_client

smtpd_data_restrictions (default: empty)

       Optional access restrictions that the Postfix SMTP  server  applies  in
       the context of the SMTP DATA command.

       This feature is available in Postfix 2.0 and later.

       Specify  a list of restrictions, separated by commas and/or whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions   are  applied  in  the  order  as  specified;  the  first
       restriction that matches wins.

       The following restrictions are valid in this context:

       ·      Generic restrictions that  can  be  used  in  any  SMTP  command
              context, described under smtpd_client_restrictions.

       ·      SMTP    command    specific    restrictions    described   under
              smtpd_client_restrictions,              smtpd_helo_restrictions,
              smtpd_sender_restrictions or smtpd_recipient_restrictions.

       Examples:

       smtpd_data_restrictions = reject_unauth_pipelining
       smtpd_data_restrictions = reject_multi_recipient_bounce

smtpd_delay_reject (default: yes)

       Wait     until     the    RCPT    TO    command    before    evaluating
       $smtpd_client_restrictions,        $smtpd_helo_restrictions         and
       $smtpd_sender_restrictions,  or  wait  until  the  ETRN  command before
       evaluating $smtpd_client_restrictions and $smtpd_helo_restrictions.

       This feature is turned on by default because  some  clients  apparently
       mis-behave  when  the  Postfix SMTP server rejects commands before RCPT
       TO.

       The default setting has one major benefit: it  allows  Postfix  to  log
       recipient  address  information when rejecting a client name/address or
       sender address, so that it is possible to find out whose mail is  being
       rejected.

smtpd_discard_ehlo_keyword_address_maps (default: empty)

       Lookup  tables,  indexed  by  the remote SMTP client address, with case
       insensitive lists of EHLO keywords (pipelining, starttls,  auth,  etc.)
       that  the  SMTP  server  will not send in the EHLO response to a remote
       SMTP client. See smtpd_discard_ehlo_keywords for details.

smtpd_discard_ehlo_keywords (default: empty)

       A case insensitive list of EHLO keywords (pipelining,  starttls,  auth,
       etc.)  that  the  SMTP  server  will not send in the EHLO response to a
       remote SMTP client.

       Notes:

       ·      Specify the silent-discard pseudo keyword to prevent this action
              from being logged.

       ·      Use   the   smtpd_discard_ehlo_keyword_address_maps  feature  to
              discard EHLO keywords selectively.

smtpd_end_of_data_restrictions (default: empty)

       Optional access restrictions that the Postfix SMTP  server  applies  in
       the context of the SMTP END-OF-DATA command.

       This feature is available in Postfix 2.2 and later.

       See smtpd_data_restrictions for syntax details.

smtpd_enforce_tls (default: no)

       Enforcement  mode:  announce  STARTTLS  support  to  SMTP  clients, and
       require that clients use TLS encryption.  According to  RFC  2487  this
       MUST NOT be applied in case of a publicly-referenced SMTP server.  This
       option is off by default and should be used only on dedicated  servers.

       Note 1: this mode implies "smtpd_tls_auth_only = yes".

       Note  2:  when  invoked  via  "sendmail  -bs", Postfix will never offer
       STARTTLS due to insufficient privileges to access  the  server  private
       key. This is intended behavior.

smtpd_error_sleep_time (default: 1s)

       With  Postfix  2.1  and  later:  the SMTP server response delay after a
       client has made more than  $smtpd_soft_error_limit  errors,  and  fewer
       than $smtpd_hard_error_limit errors, without delivering mail.

       With  Postfix  2.0  and earlier: the SMTP server delay before sending a
       reject (4xx or 5xx) response, when  the  client  has  made  fewer  than
       $smtpd_soft_error_limit errors without delivering mail.

smtpd_etrn_restrictions (default: empty)

       Optional  SMTP  server  access  restrictions in the context of a client
       ETRN request.

       The Postfix ETRN implementation  accepts  only  destinations  that  are
       eligible for the Postfix "fast flush" service. See the ETRN_README file
       for details.

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions  are  applied  in  the  order  as  specified;  the   first
       restriction that matches wins.

       The  following restrictions are specific to the domain name information
       received with the ETRN command.

       check_etrn_access type:table
              Search the specified access database for the ETRN domain name or
              its parent domains. See the access(5) manual page for details.

       Other restrictions that are valid in this context:

       ·      Generic  restrictions  that  can  be  used  in  any SMTP command
              context, described under smtpd_client_restrictions.

       ·      SMTP   command    specific    restrictions    described    under
              smtpd_client_restrictions and smtpd_helo_restrictions.

       Example:

       smtpd_etrn_restrictions = permit_mynetworks, reject

smtpd_expansion_filter (default: see postconf -d output)

       What characters are allowed in $name expansions of RBL reply templates.
       Characters not in the allowed set are replaced  by  "_".   Use  C  like
       escapes to specify special characters such as whitespace.

       This parameter is not subjected to $parameter expansion.

       This feature is available in Postfix 2.0 and later.

smtpd_forbidden_commands (default: CONNECT, GET, POST)

       List  of  commands  that  causes the Postfix SMTP server to immediately
       terminate the session with a 221 code. This can be used  to  disconnect
       clients  that obviously attempt to abuse the system. In addition to the
       commands listed in this parameter, commands that  follow  the  "Label:"
       format of message headers will also cause a disconnect.

       This feature is available in Postfix 2.2 and later.

smtpd_hard_error_limit (default: 20)

       The  maximal  number  of errors a remote SMTP client is allowed to make
       without delivering mail. The Postfix SMTP server disconnects  when  the
       limit is exceeded.

smtpd_helo_required (default: no)

       Require that a remote SMTP client introduces itself at the beginning of
       an SMTP session with the HELO or EHLO command.

       Example:

       smtpd_helo_required = yes

smtpd_helo_restrictions (default: empty)

       Optional restrictions that the  Postfix  SMTP  server  applies  in  the
       context of the SMTP HELO command.

       The default is to permit everything.

       Specify  a list of restrictions, separated by commas and/or whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions   are  applied  in  the  order  as  specified;  the  first
       restriction that matches wins.

       The following restrictions are specific  to  the  hostname  information
       received with the HELO or EHLO command.

       check_helo_access type:table
              Search  the  specified  access(5)  database for the HELO or EHLO
              hostname  or  parent  domains,  and  execute  the  corresponding
              action.

       check_helo_mx_access type:table
              Search the specified access(5) database for the MX hosts for the
              HELO or EHLO hostname, and  execute  the  corresponding  action.
              Note:  a  result  of  "OK"  is  not  allowed for safety reasons.
              Instead, use DUNNO in  order  to  exclude  specific  hosts  from
              blacklists.  This feature is available in Postfix 2.1 and later.

       check_helo_ns_access type:table
              Search the specified access(5) database for the DNS servers  for
              the HELO or EHLO hostname, and execute the corresponding action.
              Note: a result of  "OK"  is  not  allowed  for  safety  reasons.
              Instead,  use  DUNNO  in  order  to  exclude specific hosts from
              blacklists.  This feature is available in Postfix 2.1 and later.

       reject_invalid_hostname
              Reject  the  request  when  the  HELO or EHLO hostname syntax is
              invalid.
              The invalid_hostname_reject_code specifies the response code  to
              rejected requests (default: 501).

       reject_non_fqdn_hostname
              Reject  the  request  when  the  HELO or EHLO hostname is not in
              fully-qualified domain form, as required by the RFC.
              The non_fqdn_reject_code parameter specifies the  response  code
              to rejected requests (default: 504).

       reject_unknown_hostname
              Reject  the  request when the HELO or EHLO hostname has no DNS A
              or MX record.
              The unknown_hostname_reject_code specifies the response code  to
              rejected requests (default: 450).

       Other restrictions that are valid in this context:

       ·      Generic  restrictions  that  can  be  used  in  any SMTP command
              context, described under smtpd_client_restrictions.

       ·      Client  hostname  or  network  address   specific   restrictions
              described under smtpd_client_restrictions.

       ·      SMTP    command    specific    restrictions    described   under
              smtpd_sender_restrictions or smtpd_recipient_restrictions.  When
              sender    or    recipient    restrictions   are   listed   under
              smtpd_helo_restrictions,   they   have    effect    only    with
              "smtpd_delay_reject  = yes", so that $smtpd_helo_restrictions is
              evaluated at the time of the RCPT TO command.

       Examples:

       smtpd_helo_restrictions = permit_mynetworks, reject_invalid_hostname
       smtpd_helo_restrictions = permit_mynetworks, reject_unknown_hostname

smtpd_history_flush_threshold (default: 100)

       The maximal number of lines in the Postfix SMTP server command  history
       before it is flushed upon receipt of EHLO, RSET, or end of DATA.

smtpd_junk_command_limit (default: 100)

       The  number  of  junk commands (NOOP, VRFY, ETRN or RSET) that a remote
       SMTP client can send before the Postfix SMTP server starts to increment
       the  error  counter  with each junk command.  The junk command count is
       reset after mail is delivered.  See also the smtpd_error_sleep_time and
       smtpd_soft_error_limit configuration parameters.

smtpd_noop_commands (default: empty)

       List of commands that the Postfix SMTP server replies to with "250 Ok",
       without doing any syntax checks and without changing state.  This  list
       overrides any commands built into the Postfix SMTP server.

smtpd_null_access_lookup_key (default: <>)

       The  lookup key to be used in SMTP access(5) tables instead of the null
       sender address.

smtpd_policy_service_max_idle (default: 300s)

       The time after which an idle SMTPD policy service connection is closed.

       This feature is available in Postfix 2.1 and later.

smtpd_policy_service_max_ttl (default: 1000s)

       The  time  after  which  an  active  SMTPD policy service connection is
       closed.

       This feature is available in Postfix 2.1 and later.

smtpd_policy_service_timeout (default: 100s)

       The time limit for connecting  to,  writing  to  or  receiving  from  a
       delegated SMTPD policy server.

       This feature is available in Postfix 2.1 and later.

smtpd_proxy_ehlo (default: $myhostname)

       How  the  Postfix SMTP server announces itself to the proxy filter.  By
       default, the Postfix hostname is used.

       This feature is available in Postfix 2.1 and later.

smtpd_proxy_filter (default: empty)

       The hostname and TCP port of the  mail  filtering  proxy  server.   The
       proxy  receives  all mail from the Postfix SMTP server, and is supposed
       to give the result to another Postfix SMTP server process.

       Specify host:port. The host can be specified as an IP address or  as  a
       symbolic  name;  no  MX  lookups  are  done. When no host or host:  are
       specified, the local machine is assumed.

       This feature is available in Postfix 2.1 and later.

smtpd_proxy_timeout (default: 100s)

       The time limit for connecting to a proxy  filter  and  for  sending  or
       receiving  information.   When  a  connection  fails  the client gets a
       generic error message while more detailed information is logged to  the
       maillog file.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

       This feature is available in Postfix 2.1 and later.

smtpd_recipient_limit (default: 1000)

       The maximal number of recipients that the Postfix SMTP  server  accepts
       per message delivery request.

smtpd_recipient_overshoot_limit (default: 1000)

       The  number  of recipients that a remote SMTP client can send in excess
       of the limit specified with $smtpd_recipient_limit, before the  Postfix
       SMTP  server  increments  the  per-session  error count for each excess
       recipient.

smtpd_recipient_restrictions (default: permit_mynetworks,

       reject_unauth_destination)
       The  access  restrictions  that  the Postfix SMTP server applies in the
       context of the RCPT TO command.

       By default, the Postfix SMTP server accepts:

       ·      Mail from clients whose IP address matches $mynetworks, or:

       ·      Mail to remote destinations that  match  $relay_domains,  except
              for    addresses    that    contain   sender-specified   routing
              (user@elsewhere@domain), or:

       ·      Mail  to  local  destinations  that  match  $inet_interfaces  or
              $proxy_interfaces,  $mydestination,  $virtual_alias_domains,  or
              $virtual_mailbox_domains.

       IMPORTANT: If you change this parameter setting, you  must  specify  at
       least  one of the following restrictions. Otherwise Postfix will refuse
       to receive mail:

           reject, defer, defer_if_permit, reject_unauth_destination

       Specify a list of restrictions, separated by commas and/or  whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions  are  applied  in  the  order  as  specified;  the   first
       restriction that matches wins.

       The  following  restrictions are specific to the recipient address that
       is received with the RCPT TO command.

       check_recipient_access type:table
              Search the specified access(5) database for the resolved RCPT TO
              address,  domain, parent domains, or localpart@, and execute the
              corresponding action.

       check_recipient_mx_access type:table
              Search the specified access(5) database for the MX hosts for the
              RCPT  TO address, and execute the corresponding action.  Note: a
              result of "OK" is not allowed for safety reasons.  Instead,  use
              DUNNO  in order to exclude specific hosts from blacklists.  This
              feature is available in Postfix 2.1 and later.

       check_recipient_ns_access type:table
              Search the specified access(5) database for the DNS servers  for
              the  RCPT  TO  address,  and  execute  the corresponding action.
              Note: a result of  "OK"  is  not  allowed  for  safety  reasons.
              Instead,  use  DUNNO  in  order  to  exclude specific hosts from
              blacklists.  This feature is available in Postfix 2.1 and later.

       permit_auth_destination
              Permit the request when one of the following is true:

       ·      Postfix  is mail forwarder: the resolved RCPT TO address matches
              $relay_domains or a subdomain thereof, and the address  contains
              no sender-specified routing (user@elsewhere@domain),

       ·      Postfix  is  the final destination: the resolved RCPT TO address
              matches  $mydestination,  $inet_interfaces,   $proxy_interfaces,
              $virtual_alias_domains,  or  $virtual_mailbox_domains,  and  the
              address      contains      no      sender-specified      routing
              (user@elsewhere@domain).

       permit_mx_backup
              Permit the request when the local mail system is MX host for the
              RCPT TO address. This includes the  case  that  the  local  mail
              system  is  the final destination. However, the SMTP server will
              not forward  mail  with  addresses  that  have  sender-specified
              routing  information  (example: user@elsewhere@domain).  Use the
              optional permit_mx_backup_networks parameter to require that the
              primary MX hosts match a list of network blocks.
              Note:  prior  to Postfix version 2.0, use of permit_mx_backup is
              not recommended; mail may be rejected in case of a temporary DNS
              lookup problem.

       reject_non_fqdn_recipient
              Reject  the  request  when  the RCPT TO address is not in fully-
              qualified domain form, as required by the RFC.
              The non_fqdn_reject_code parameter specifies the  response  code
              to rejected requests (default: 504).

       reject_rhsbl_recipient rbl_domain=d.d.d.d
              Reject  the request when the RCPT TO domain is listed with the A
              record "d.d.d.d" under rbl_domain (Postfix version 2.1 and later
              only).   If  no "=d.d.d.d" is specified, reject the request when
              the reversed client network address is listed with any A  record
              under rbl_domain.
              The  maps_rbl_reject_code  parameter specifies the response code
              for rejected  requests  (default:  554);  the  default_rbl_reply
              parameter   specifies   the   default   server  reply;  and  the
              rbl_reply_maps parameter specifies tables  with  server  replies
              indexed by rbl_domain.  This feature is available in Postfix 2.0
              and later.

       reject_unauth_destination
              Reject the request unless one of the following is true:

       ·      Postfix is mail forwarder: the resolved RCPT TO address  matches
              $relay_domains  or  a subdomain thereof, and contains no sender-
              specified routing (user@elsewhere@domain),

       ·      Postfix is the final destination: the resolved RCPT  TO  address
              matches   $mydestination,  $inet_interfaces,  $proxy_interfaces,
              $virtual_alias_domains,   or    $virtual_mailbox_domains,    and
              contains no sender-specified routing (user@elsewhere@domain).
               The  relay_domains_reject_code parameter specifies the response
              code for rejected requests (default: 554).

       reject_unknown_recipient_domain
              Reject the request when the RCPT TO address has no DNS A  or  MX
              record  and  Postfix  is not final destination for the recipient
              address.
              The unknown_address_reject_code parameter specifies the response
              code  for  rejected  requests  (default:  450).  The response is
              always 450 in case of a temporary DNS error.

       reject_unlisted_recipient (Postfix 2.0 name: check_recipient_maps)
              Reject the request when the RCPT TO address is not listed in the
              list   of  valid  recipients  for  its  domain  class.  See  the
              smtpd_reject_unlisted_recipient   parameter   description    for
              details.  This feature is available in Postfix 2.1 and later.

       reject_unverified_recipient
              Reject  the request when mail to the RCPT TO address is known to
              bounce,  or  when  the  recipient  address  destination  is  not
              reachable.   Address  verification information is managed by the
              verify(8) server; see the ADDRESS_VERIFICATION_README  file  for
              details.
              The  unverified_recipient_reject_code  parameter  specifies  the
              response when an address  is  known  to  bounce  (default:  450,
              change  into  550  when  you are confident that it is safe to do
              so). Postfix replies with 450 when an address probe  failed  due
              to  a  temporary  problem.  This feature is available in Postfix
              2.1 and later.

       Other restrictions that are valid in this context:

       ·      Generic restrictions that  can  be  used  in  any  SMTP  command
              context, described under smtpd_client_restrictions.

       ·      SMTP    command    specific    restrictions    described   under
              smtpd_client_restrictions,      smtpd_helo_restrictions      and
              smtpd_sender_restrictions.

       Example:

       smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination

smtpd_reject_unlisted_recipient (default: yes)

       Request that the Postfix SMTP server rejects mail for unknown recipient
       addresses,  even  when  no  explicit  reject_unlisted_recipient  access
       restriction  is specified. This prevents the Postfix queue from filling
       up with undeliverable MAILER-DAEMON messages.

       ·      The recipient domain matches $mydestination, $inet_interfaces or
              $proxy_interfaces,   but   the   recipient   is  not  listed  in
              $local_recipient_maps, and $local_recipient_maps is not null.

       ·      The recipient  domain  matches  $virtual_alias_domains  but  the
              recipient is not listed in $virtual_alias_maps.

       ·      The  recipient  domain  matches $virtual_mailbox_domains but the
              recipient  is   not   listed   in   $virtual_mailbox_maps,   and
              $virtual_mailbox_maps is not null.

       ·      The recipient domain matches $relay_domains but the recipient is
              not listed in $relay_recipient_maps,  and  $relay_recipient_maps
              is not null.

       This feature is available in Postfix 2.1 and later.

smtpd_reject_unlisted_sender (default: no)

       Request  that  the Postfix SMTP server rejects mail from unknown sender
       addresses,  even  when  no   explicit   reject_unlisted_sender   access
       restriction  is  specified.  This  can slow down an explosion of forged
       mail from worms or viruses.

       ·      The sender domain matches  $mydestination,  $inet_interfaces  or
              $proxy_interfaces,   but   the   sender   is   not   listed   in
              $local_recipient_maps, and $local_recipient_maps is not null.

       ·      The sender domain matches $virtual_alias_domains but the  sender
              is not listed in $virtual_alias_maps.

       ·      The  sender  domain  matches  $virtual_mailbox_domains  but  the
              sender   is   not   listed   in    $virtual_mailbox_maps,    and
              $virtual_mailbox_maps is not null.

       ·      The  sender  domain matches $relay_domains but the sender is not
              listed in $relay_recipient_maps,  and  $relay_recipient_maps  is
              not null.

       This feature is available in Postfix 2.1 and later.

smtpd_restriction_classes (default: empty)

       User-defined aliases for groups of access restrictions. The aliases can
       be specified in smtpd_recipient_restrictions etc., and  on  the  right-
       hand side of a Postfix access(5) table.

       One  major  application  is for implementing per-recipient UCE control.
       See the RESTRICTION_CLASS_README document for other examples.

smtpd_sasl_application_name (default: smtpd)

       The application name used for SASL server initialization. This controls
       the  name  of  the SASL configuration file. The default value is smtpd,
       corresponding to a SASL configuration file named smtpd.conf.

       This feature is available in Postfix 2.1 and later.

smtpd_sasl_auth_enable (default: no)

       Enable SASL authentication in the Postfix SMTP server. By default,  the
       Postfix SMTP server does not use authentication.

       If a remote SMTP client is authenticated, the permit_sasl_authenticated
       access restriction can be used to permit relay access, like this:

           smtpd_recipient_restrictions =
               permit_mynetworks, permit_sasl_authenticated, ...

       To reject all SMTP connections from  unauthenticated  clients,  specify
       "smtpd_delay_reject = yes" (which is the default) and use:

           smtpd_client_restrictions = permit_sasl_authenticated, reject

       See  the SASL_README file for SASL configuration and operation details.

smtpd_sasl_exceptions_networks (default: empty)

       What SMTP clients Postfix will not offer AUTH support to.

       Some clients (Netscape 4 at least) have  a  bug  that  causes  them  to
       require  a  login  and  password whenever AUTH is offered, whether it’s
       necessary  or  not.  To  work  around  this,  specify,   for   example,
       $mynetworks to prevent Postfix from offering AUTH to local clients.

       Specify  a list of network/netmask patterns, separated by commas and/or
       whitespace. The mask specifies the number of bits in the  network  part
       of  a host address. You can also "/file/name" or "type:table" patterns.
       A "/file/name" pattern is replaced  by  its  contents;  a  "type:table"
       lookup table is matched when a table entry matches a lookup string (the
       lookup result is ignored).  Continue long lines by  starting  the  next
       line with whitespace.

       Note:  IP  version 6 address information must be specified inside [] in
       the smtpd_sasl_exceptions_networks value, and in files  specified  with
       "/file/name".   IP  version  6 addresses contain the ":" character, and
       would otherwise be confused with a "type:table" pattern.

       Example:

       smtpd_sasl_exceptions_networks = $mynetworks

       This feature is available in Postfix 2.1 and later.

smtpd_sasl_local_domain (default: empty)

       The name of the local SASL authentication realm.

       By default, the local authentication realm name is the null string.

       Examples:

       smtpd_sasl_local_domain = $mydomain
       smtpd_sasl_local_domain = $myhostname

smtpd_sasl_security_options (default: noanonymous)

       Restrict what authentication mechanisms the Postfix  SMTP  server  will
       offer  to  the client.  The list of available authentication mechanisms
       is system dependent.

       Specify zero or more of the following:

       noplaintext
              Disallow methods that use plaintext passwords.

       noactive
              Disallow methods subject to active (non-dictionary) attack.

       nodictionary
              Disallow methods subject to passive (dictionary) attack.

       noanonymous
              Disallow methods that allow anonymous authentication.

       mutual_auth
              Only allow  methods  that  provide  mutual  authentication  (not
              available with SASL version 1).

       By default, the Postfix SMTP server accepts plaintext passwords but not
       anonymous logins.

       Warning: it appears that clients  try  authentication  methods  in  the
       order  as  advertised  by  the  server (e.g., PLAIN ANONYMOUS CRAM-MD5)
       which means that if you disable plaintext passwords, clients  will  log
       in  anonymously, even when they should be able to use CRAM-MD5.  So, if
       you disable plaintext logins, disable anonymous  logins  too.   Postfix
       treats anonymous login as no authentication.

       Example:

       smtpd_sasl_security_options = noanonymous, noplaintext

smtpd_sasl_tls_security_options (default: $smtpd_sasl_security_options)

       The  SASL  authentication security options that the Postfix SMTP server
       uses for TLS encrypted SMTP sessions.

smtpd_sender_login_maps (default: empty)

       Optional lookup table with the SASL login names that own  sender  (MAIL
       FROM) addresses.

       Specify  zero  or  more  "type:table"  lookup tables. With lookups from
       indexed files such as DB or DBM, or from networked tables such as  NIS,
       LDAP  or  SQL,  the  following search operations are done with a sender
       address of user@domain:

       1) user@domain
              This table lookup is always done and has the highest precedence.

       2) user
              This  table  lookup  is  done  only  when the domain part of the
              sender    address     matches     $myorigin,     $mydestination,
              $inet_interfaces or $proxy_interfaces.

       3) @domain
              This table lookup is done last and has the lowest precedence.

       In all cases the result of table lookup must be either "not found" or a
       list of SASL login names separated by comma and/or whitespace.

smtpd_sender_restrictions (default: empty)

       Optional restrictions that the  Postfix  SMTP  server  applies  in  the
       context of the MAIL FROM command.

       The default is to permit everything.

       Specify  a list of restrictions, separated by commas and/or whitespace.
       Continue  long  lines  by  starting  the  next  line  with  whitespace.
       Restrictions   are  applied  in  the  order  as  specified;  the  first
       restriction that matches wins.

       The following restrictions are specific to the sender address  received
       with the MAIL FROM command.

       check_sender_access type:table
              Search  the  specified  access(5)  database  for  the  MAIL FROM
              address, domain, parent domains, or localpart@, and execute  the
              corresponding action.

       check_sender_mx_access type:table
              Search the specified access(5) database for the MX hosts for the
              MAIL FROM address, and execute the corresponding action.   Note:
              a result of "OK" is not allowed for safety reasons. Instead, use
              DUNNO in order to exclude specific hosts from blacklists.   This
              feature is available in Postfix 2.1 and later.

       check_sender_ns_access type:table
              Search  the specified access(5) database for the DNS servers for
              the MAIL FROM address, and  execute  the  corresponding  action.
              Note:  a  result  of  "OK"  is  not  allowed for safety reasons.
              Instead, use DUNNO in  order  to  exclude  specific  hosts  from
              blacklists.  This feature is available in Postfix 2.1 and later.

       reject_authenticated_sender_login_mismatch
              Enforces  the   reject_sender_login_mismatch   restriction   for
              authenticated clients only. This feature is available in Postfix
              version 2.1 and later.

       reject_non_fqdn_sender
              Reject the request when the MAIL FROM address is not  in  fully-
              qualified domain form, as required by the RFC.
              The  non_fqdn_reject_code  parameter specifies the response code
              to rejected requests (default: 504).

       reject_rhsbl_sender rbl_domain=d.d.d.d
              Reject the request when the MAIL FROM domain is listed with  the
              A  record  "d.d.d.d"  under  rbl_domain (Postfix version 2.1 and
              later only).  If no "=d.d.d.d" is specified, reject the  request
              when  the  reversed  client network address is listed with any A
              record under rbl_domain.
              The maps_rbl_reject_code parameter specifies the  response  code
              for  rejected  requests  (default:   554); the default_rbl_reply
              parameter  specifies  the  default   server   reply;   and   the
              rbl_reply_maps  parameter  specifies  tables with server replies
              indexed by rbl_domain.  This feature is available in Postfix 2.0
              and later.

       reject_sender_login_mismatch
              Reject  the  request  when $smtpd_sender_login_maps specifies an
              owner for the MAIL FROM address, but the client  is  not  (SASL)
              logged in as that MAIL FROM address owner; or when the client is
              (SASL) logged in, but the client login name doesn’t own the MAIL
              FROM address according to $smtpd_sender_login_maps.

       reject_unauthenticated_sender_login_mismatch
              Enforces   the   reject_sender_login_mismatch   restriction  for
              unauthenticated clients  only.  This  feature  is  available  in
              Postfix version 2.1 and later.

       reject_unknown_sender_domain
              Reject the request when the MAIL FROM address has no DNS A or MX
              record and Postfix is  not  final  destination  for  the  sender
              address.
              The unknown_address_reject_code parameter specifies the response
              code for rejected requests  (default:  450).   The  response  is
              always 450 in case of a temporary DNS error.

       reject_unlisted_sender
              Reject  the  request when the MAIL FROM address is not listed in
              the list of valid recipients  for  its  domain  class.  See  the
              smtpd_reject_unlisted_sender  parameter description for details.
              This feature is available in Postfix 2.1 and later.

       reject_unverified_sender
              Reject the request when mail to the MAIL FROM address  is  known
              to  bounce,  or  when  the  sender  address  destination  is not
              reachable.  Address verification information is managed  by  the
              verify(8)  server;  see the ADDRESS_VERIFICATION_README file for
              details.
              The  unverified_sender_reject_code   parameter   specifies   the
              response  when  an  address  is  known  to bounce (default: 450,
              change into 550 when you are confident that it  is  safe  to  do
              so).  Postfix  replies with 450 when an address probe failed due
              to a temporary problem.  This feature is  available  in  Postfix
              2.1 and later.

       Other restrictions that are valid in this context:

       ·      Generic  restrictions  that  can  be  used  in  any SMTP command
              context, described under smtpd_client_restrictions.

       ·      SMTP   command    specific    restrictions    described    under
              smtpd_client_restrictions and smtpd_helo_restrictions.

       ·      SMTP    command    specific    restrictions    described   under
              smtpd_recipient_restrictions. When  recipient  restrictions  are
              listed  under  smtpd_sender_restrictions,  they have effect only
              with     "smtpd_delay_reject      =      yes",      so      that
              $smtpd_sender_restrictions  is evaluated at the time of the RCPT
              TO command.

       Examples:

       smtpd_sender_restrictions = reject_unknown_sender_domain
       smtpd_sender_restrictions = reject_unknown_sender_domain,
           check_sender_access hash:/etc/postfix/access

smtpd_soft_error_limit (default: 10)

       The number of errors a remote SMTP client is allowed  to  make  without
       delivering  mail  before  the  Postfix  SMTP  server slows down all its
       responses.

       ·      With Postfix version 2.1 and  later,  the  Postfix  SMTP  server
              delays all responses by $smtpd_error_sleep_time seconds.

       ·      With  Postfix  versions 2.0 and earlier, the Postfix SMTP server
              delays all responses by (number of errors) seconds.

smtpd_starttls_timeout (default: 300s)

       The time limit for Postfix SMTP server write and read operations during
       TLS startup and shutdown handshake procedures.

smtpd_timeout (default: 300s)

       The  time  limit  for  sending  a  Postfix SMTP server response and for
       receiving a remote SMTP client request.

       Note: if you set SMTP time limits to very large values you may have  to
       update the global ipc_timeout parameter.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

smtpd_tls_CAfile (default: empty)

       The file with the certificate of the certification authority (CA)  that
       issued  the  Postfix SMTP server certificate.  This is needed only when
       the CA certificate is not already present  in  the  server  certificate
       file.   This file may also contain the CA certificates of other trusted
       CAs.  You must use this file for the list of trusted CAs if you want to
       use chroot-mode.

       Example:

       smtpd_tls_CAfile = /etc/postfix/CAcert.pem

smtpd_tls_CApath (default: empty)

       Directory  with  PEM format certificate authority certificates that the
       Postfix SMTP server offers to remote SMTP clients for  the  purpose  of
       client certificate verification.  Do not forget to create the necessary
       "hash"   links   with,   for    example,    "$OPENSSL_HOME/bin/c_rehash
       /etc/postfix/certs".

       To  use  this option in chroot mode, this directory (or a copy) must be
       inside  the  chroot  jail.  Please  note  that  in  this  case  the  CA
       certificates  are  not  offered  to  the client, so that e.g.  Netscape
       clients might not offer certificates  issued  by  them.   Use  of  this
       feature is therefore not recommended.

       Example:

       smtpd_tls_CApath = /etc/postfix/certs

smtpd_tls_ask_ccert (default: no)

       Ask  a remote SMTP client for a client certificate. This information is
       needed for certificate based  mail  relaying  with,  for  example,  the
       permit_tls_clientcerts feature.

       Some clients such as Netscape will either complain if no certificate is
       available (for the list of CAs in  /etc/postfix/certs)  or  will  offer
       multiple  client  certificates to choose from. This may be annoying, so
       this option is "off" by default.

smtpd_tls_auth_only (default: no)

       When TLS encryption is optional in the  Postfix  SMTP  server,  do  not
       announce or accept SASL authentication over unencrypted connections.

smtpd_tls_ccert_verifydepth (default: 5)

       The  verification depth for remote SMTP client certificates. A depth of
       1 is sufficient if the issuing CA is listed in a local  CA  file.   The
       default value should also suffice for longer chains (the root CA issues
       special CA which then issues the actual certificate...).

smtpd_tls_cert_file (default: empty)

       File with the Postfix SMTP server RSA certificate in PEM format.   This
       file may also contain the server private key.

       Both  RSA  and  DSA  certificates  are  supported.  When both types are
       present, the cipher used determines which certificate will be presented
       to the client.  For Netscape and OpenSSL clients without special cipher
       choices the RSA certificate is preferred.

       In order to verify a certificate, the CA  certificate  (in  case  of  a
       certificate  chain, all CA certificates) must be available.  You should
       add  these  certificates  to  the  server   certificate,   the   server
       certificate first, then the issuing CA(s).

       Example:   the   certificate   for   "server.dom.ain"   was  issued  by
       "intermediate CA" which itself has a certificate of "root CA".   Create
       the  server.pem  file  with  "cat  server_cert.pem  intermediate_CA.pem
       root_CA.pem > server.pem".

       If you want to accept certificates issued by these  CAs  yourself,  you
       can also add the CA certificates to the smtpd_tls_CAfile, in which case
       it is not  necessary  to  have  them  in  the  smtpd_tls_dcert_file  or
       smtpd_tls_cert_file.

       A  certificate  supplied  here must be usable as SSL server certificate
       and hence pass the "openssl verify -purpose sslserver ..." test.

       Example:

       smtpd_tls_cert_file = /etc/postfix/server.pem

smtpd_tls_cipherlist (default: empty)

       Controls the Postfix SMTP server  TLS  cipher  selection  scheme.   For
       details,  see  the  OpenSSL  documentation.  Note: do not use "" quotes
       around the parameter value.

smtpd_tls_dcert_file (default: empty)

       File with the Postfix SMTP server DSA certificate in PEM format.   This
       file may also contain the server private key.

       See the discussion under smtpd_tls_cert_file for more details.

       Example:

       smtpd_tls_dcert_file = /etc/postfix/server-dsa.pem

smtpd_tls_dh1024_param_file (default: empty)

       File  with  DH  parameters that the Postfix SMTP server should use with
       EDH ciphers.

       Instead of using the exact same  parameter  sets  as  distributed  with
       other  TLS  packages,  it  is  more  secure to generate your own set of
       parameters with something like the following command:

       openssl gendh -out /etc/postfix/dh_1024.pem -2 -rand /var/run/egd-pool 1024

       Your  actual  source  for  entropy  may  differ.  Some   systems   have
       /dev/random;  on  other  system  you  may  consider  using the "Entropy
       Gathering Daemon EGD", available at http://www.lothar.com/tech/crypto/.

       Example:

       smtpd_tls_dh1024_param_file = /etc/postfix/dh_1024.pem

smtpd_tls_dh512_param_file (default: empty)

       File  with  DH  parameters that the Postfix SMTP server should use with
       EDH ciphers.

       See  also  the   discussion   under   the   smtpd_tls_dh1024_param_file
       configuration parameter.

       Example:

       smtpd_tls_dh512_param_file = /etc/postfix/dh_512.pem

smtpd_tls_dkey_file (default: $smtpd_tls_dcert_file)

       File  with the Postfix SMTP server DSA private key in PEM format.  This
       file may be combined with the server certificate  file  specified  with
       $smtpd_tls_dcert_file.

       The  private key must not be encrypted. In other words, the key must be
       accessible without password.

smtpd_tls_key_file (default: $smtpd_tls_cert_file)

       File with the Postfix SMTP server RSA private key in PEM format.   This
       file  may  be  combined with the server certificate file specified with
       $smtpd_tls_cert_file.

       The private key must not be encrypted. In other words, the key must  be
       accessible without password.

smtpd_tls_loglevel (default: 0)

       Enable  additional  Postfix  SMTP server logging of TLS activity.  Each
       logging level also includes the information that is logged at  a  lower
       logging level.

              0 Disable logging of TLS activity.

              1 Log TLS handshake and certificate information.

              2 Log levels during TLS negotiation.

              3 Log hexadecimal and ASCII dump of TLS negotiation process.

              4  Also  log hexadecimal and ASCII dump of complete transmission
              after STARTTLS.

       Use "smtpd_tls_loglevel = 3" only in case of problems. Use of  loglevel
       4 is strongly discouraged.

smtpd_tls_received_header (default: no)

       Request  that  the  Postfix  SMTP  server  produces  Received:  message
       headers that include information about the protocol and cipher used, as
       well as the client CommonName and client certificate issuer CommonName.
       This is disabled by default, as the  information  may  be  modified  in
       transit through other mail servers.  Only information that was recorded
       by the final destination can be trusted.

smtpd_tls_req_ccert (default: no)

       When  TLS  encryption  is  enforced,  require  a  remote  SMTP   client
       certificate  in order to allow TLS connections to proceed.  This option
       implies "smtpd_tls_ask_ccert = yes".

       When TLS encryption is optional, remote SMTP  clients  can  bypass  the
       restriction  by simply not using STARTTLS at all. For this reason a TLS
       connection will be handled as if only "smtpd_tls_ask_ccert  =  yes"  is
       specified.

smtpd_tls_session_cache_database (default: empty)

       Name  of  the  file  containing  the  optional  Postfix SMTP server TLS
       session cache. Specify a database type that supports enumeration,  such
       as  btree  or sdbm; there is no need to support concurrent access.  The
       file is created if it does not exist.

       Note: dbm databases are not  suitable.  TLS  session  objects  are  too
       large.

       Example:

       smtpd_tls_session_cache_database = btree:/var/postfix/smtpd_scache

smtpd_tls_session_cache_timeout (default: 3600s)

       The   expiration   time  of  Postfix  SMTP  server  TLS  session  cache
       information.   A  cache  cleanup  is   performed   periodically   every
       $smtpd_tls_session_cache_timeout seconds.

smtpd_tls_wrappermode (default: no)

       Run the Postfix SMTP server in the non-standard "wrapper" mode, instead
       of using the STARTTLS command.

       If you  want  to  support  this  service,  enable  a  special  port  in
       master.cf,  and  specify  "-o  smtpd_tls_wrappermode=yes"  on  the SMTP
       server’s command line. Port  465  (smtps)  was  once  chosen  for  this
       purpose.

smtpd_use_tls (default: no)

       Opportunistic  mode:  announce STARTTLS support to SMTP clients, but do
       not require that clients use TLS encryption.

       Note: when  invoked  via  "sendmail  -bs",  Postfix  will  never  offer
       STARTTLS  due  to  insufficient privileges to access the server private
       key. This is intended behavior.

soft_bounce (default: no)

       Safety net to keep mail queued that would otherwise be returned to  the
       sender.    This   parameter  disables  locally-generated  bounces,  and
       prevents the Postfix SMTP server from rejecting  mail  permanently,  by
       changing 5xx reply codes into 4xx.  However, soft_bounce is no cure for
       address rewriting mistakes or mail routing mistakes.

       Example:

       soft_bounce = yes

stale_lock_time (default: 500s)

       The time after which a stale exclusive  mailbox  lockfile  is  removed.
       This is used for delivery to file or mailbox.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

strict_7bit_headers (default: no)

       Reject mail with 8-bit text in message headers. This blocks  mail  from
       poorly written applications.

       This  feature  should  not be enabled on a general purpose mail server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0 and later.

strict_8bitmime (default: no)

       Enable both strict_7bit_headers and strict_8bitmime_body.

       This feature should not be enabled on a general  purpose  mail  server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0 and later.

strict_8bitmime_body (default: no)

       Reject  8-bit  message  body  text  without 8-bit MIME content encoding
       information.  This blocks mail from poorly written applications.

       Unfortunately, this also rejects majordomo approval requests  when  the
       included request contains valid 8-bit MIME mail, and it rejects bounces
       from mailers that do not MIME encapsulate 8-bit content  (for  example,
       bounces from qmail or from old versions of Postfix).

       This  feature  should  not be enabled on a general purpose mail server,
       because it is likely to reject legitimate email.

       This feature is available in Postfix 2.0 and later.

strict_mime_encoding_domain (default: no)

       Reject mail with invalid Content-Transfer-Encoding: information for the
       message/*  or  multipart/*  MIME  content types.  This blocks mail from
       poorly written software.

       This feature should not be enabled on a general  purpose  mail  server,
       because it will reject mail after a single violation.

       This feature is available in Postfix 2.0 and later.

strict_rfc821_envelopes (default: no)

       Require  that addresses received in SMTP MAIL FROM and RCPT TO commands
       are enclosed with <>, and that those addresses do not contain  RFC  822
       style  comments  or  phrases.   This  stops  mail  from  poorly written
       software.

       By default, the Postfix SMTP server accepts RFC 822 syntax in MAIL FROM
       and RCPT TO addresses.

sun_mailtool_compatibility (default: no)

       Obsolete    SUN    mailtool   compatibility   feature.   Instead,   use
       "mailbox_delivery_lock = dotlock".

swap_bangpath (default: yes)

       Enable  the  rewriting  of  "site!user"  into  "user@site".   This   is
       necessary if your machine is connected to UUCP networks.  It is enabled
       by default.

       Note: with  Postfix  version  2.2,  message  header  address  rewriting
       happens only when one of the following conditions is true:

       ·      The message is received with the Postfix sendmail(1) command,

       ·      The  message  is  received  from  a  network client that matches
              $local_header_rewrite_clients,

       ·      The  message   is   received   from   the   network,   and   the
              remote_header_rewrite_domain  parameter  specifies  a  non-empty
              value.

       To    get    the    behavior    before     Postfix     2.2,     specify
       "local_header_rewrite_clients = static:all".

       Example:

       swap_bangpath = no

syslog_facility (default: mail)

       The  syslog  facility of Postfix logging. Specify a facility as defined
       in syslog.conf(5). The default facility is "mail".

       Warning: a non-default syslog_facility setting takes effect only  after
       a  Postfix process has completed initialization.  Errors during process
       initialization will be logged with the default facility.  Examples  are
       errors  while  parsing  the  command  line  arguments, and errors while
       accessing the Postfix main.cf configuration file.

syslog_name (default: postfix)

       The mail system name that is prepended to the process  name  in  syslog
       records, so that "smtpd" becomes, for example, "postfix/smtpd".

       Warning:  a  non-default  syslog_name setting takes effect only after a
       Postfix process has completed  initialization.  Errors  during  process
       initialization  will  be  logged  with  the  default name. Examples are
       errors while parsing the  command  line  arguments,  and  errors  while
       accessing the Postfix main.cf configuration file.

tls_daemon_random_bytes (default: 32)

       The  number  of pseudo-random bytes that an smtp(8) or smtpd(8) process
       requests from the tlsmgr(8) server in order to seed its internal pseudo
       random number generator (PRNG).  The default of 32 bytes (equivalent to
       256 bits) is sufficient to generate a 128bit (or 168bit) session key.

tls_random_bytes (default: 32)

       The number of bytes that tlsmgr(8) reads from  $tls_random_source  when
       (re)seeding  the  in-memory pseudo random number generator (PRNG) pool.
       The default of 32 bytes (256 bits) is good enough for 128bit  symmetric
       keys.  If using EGD or a device file, a maximum of 255 bytes is read.

tls_random_exchange_name (default: ${config_directory}/prng_exch)

       Name  of  the  pseudo random number generator (PRNG) state file that is
       maintained by tlsmgr(8). The file is created when it  does  not  exist,
       and its length is fixed at 1024 bytes.

       Since  this  file is modified by Postfix, it should probably be kept in
       the /var file system, instead of under $config_directory.  The location
       should not be inside the chroot jail.

tls_random_prng_update_period (default: 3600s)

       The  time between attempts by tlsmgr(8) to save the state of the pseudo
       random  number  generator   (PRNG)   to   the   file   specified   with
       $tls_random_exchange_name.

tls_random_reseed_period (default: 3600s)

       The maximal time between attempts by tlsmgr(8) to re-seed the in-memory
       pseudo random number generator (PRNG) pool from external sources.   The
       actual  time  between re-seeding attempts is calculated using the PRNG,
       and is between 0 and the time specified.

tls_random_source (default: see postconf -d output)

       The external entropy source for the in-memory tlsmgr(8)  pseudo  random
       number generator (PRNG) pool. Be sure to specify a non-blocking source.
       If this source is not a regular file, the entropy source type  must  be
       prepended:   egd:/path/to/egd_socket  for  a source with EGD compatible
       socket interface, or dev:/path/to/device for a device file.

       Note: on OpenBSD systems specify /dev/arandom when  /dev/urandom  gives
       timeout errors.

trace_service_name (default: trace)

       The  name  of  the trace(8) service. This service maintains a record of
       mail deliveries and  produces  a  mail  delivery  report  when  verbose
       delivery is requested with "sendmail -v".

       This feature is available in Postfix 2.1 and later.

transport_maps (default: empty)

       Optional lookup tables with mappings from recipient address to (message
       delivery  transport,  next-hop  destination).   See  transport(5)   for
       details.

       Specify  zero  or  more  "type:table"  lookup  tables.  If you use this
       feature with local files, run  "postmap  /etc/postfix/transport"  after
       making a change.

       Examples:

       transport_maps = dbm:/etc/postfix/transport
       transport_maps = hash:/etc/postfix/transport

transport_retry_time (default: 60s)

       The  time  between  attempts  by the Postfix queue manager to contact a
       malfunctioning message delivery transport.

       Time units: s (seconds), m (minutes), h (hours), d (days),  w  (weeks).
       The default time unit is s (seconds).

trigger_timeout (default: 10s)

       The  time limit for sending a trigger to a Postfix daemon (for example,
       the pickup(8) or qmgr(8) daemon). This  time  limit  prevents  programs
       from getting stuck when the mail system is under heavy load.

       Time  units:  s (seconds), m (minutes), h (hours), d (days), w (weeks).
       The default time unit is s (seconds).

undisclosed_recipients_header (default: To: undisclosed-recipients:;)

       Message header that  the  Postfix  cleanup(8)  server  inserts  when  a
       message contains no To: or Cc: message header.

unknown_address_reject_code (default: 450)

       The  numerical  Postfix  SMTP  server  response  code  when a sender or
       recipient address is rejected by  the  reject_unknown_sender_domain  or
       reject_unknown_recipient_domain restriction.

       Do not change this unless you have a complete understanding of RFC 821.

unknown_client_reject_code (default: 450)

       The numerical Postfix SMTP server response code when a  client  without
       valid address <=> name mapping is rejected by the reject_unknown_client
       restriction. The SMTP server always replies with 450 when  the  mapping
       failed due to a temporary error condition.

       Do not change this unless you have a complete understanding of RFC 821.

unknown_hostname_reject_code (default: 450)

       The numerical Postfix SMTP  server  response  code  when  the  hostname
       specified   with   the   HELO  or  EHLO  command  is  rejected  by  the
       reject_unknown_hostname restriction.

       Do not change this unless you have a complete understanding of RFC 821.

unknown_local_recipient_reject_code (default: 550)

       The  numerical  Postfix  SMTP  server  response  code  when a recipient
       address is local, and $local_recipient_maps specifies a list of  lookup
       tables that does not match the recipient.  A recipient address is local
       when  its   domain   matches   $mydestination,   $proxy_interfaces   or
       $inet_interfaces.

       The  default  setting is 550 (reject mail) but it is safer to initially
       use 450 (try again later)  so  you  have  time  to  find  out  if  your
       local_recipient_maps settings are OK.

       Example:

       unknown_local_recipient_reject_code = 450

       This feature is available in Postfix 2.0 and later.

unknown_relay_recipient_reject_code (default: 550)

       The  numerical  Postfix SMTP server reply code when a recipient address
       matches $relay_domains, and relay_recipient_maps specifies  a  list  of
       lookup tables that does not match the recipient address.

       This feature is available in Postfix 2.0 and later.

unknown_virtual_alias_reject_code (default: 550)

       The   SMTP   server   reply  code  when  a  recipient  address  matches
       $virtual_alias_domains, and $virtual_alias_maps  specifies  a  list  of
       lookup tables that does not match the recipient address.

       This feature is available in Postfix 2.0 and later.

unknown_virtual_mailbox_reject_code (default: 550)

       The   SMTP   server   reply  code  when  a  recipient  address  matches
       $virtual_mailbox_domains, and $virtual_mailbox_maps specifies a list of
       lookup tables that does not match the recipient address.

       This feature is available in Postfix 2.0 and later.

unverified_recipient_reject_code (default: 450)

       The  numerical Postfix SMTP server response when a recipient address is
       rejected by the reject_unverified_recipient restriction.

       Unlike elsewhere in Postfix, you can specify 250 in order to accept the
       address anyway.

       Do not change this unless you have a complete understanding of RFC 821.

       This feature is available in Postfix 2.1 and later.

unverified_sender_reject_code (default: 450)

       The numerical Postfix  SMTP  server  response  code  when  a  recipient
       address is rejected by the reject_unverified_sender restriction.

       Unlike elsewhere in Postfix, you can specify 250 in order to accept the
       address anyway.

       Do not change this unless you have a complete understanding of RFC 821.

       This feature is available in Postfix 2.1 and later.

verp_delimiter_filter (default: -=+)

       The  characters  Postfix  accepts  as  VERP delimiter characters on the
       Postfix sendmail(1) command line and in SMTP commands.

       This feature is available in Postfix 1.1 and later.

virtual_alias_domains (default: $virtual_alias_maps)

       Postfix is final destination for the specified list  of  virtual  alias
       domains,  that  is,  domains  for  which  all  addresses are aliased to
       addresses in other local or remote domains. The SMTP  server  validates
       recipient  addresses  with $virtual_alias_maps and rejects non-existent
       recipients.  See  also  the  virtual  alias   domain   class   in   the
       ADDRESS_CLASS_README file

       This  feature  is available in Postfix 2.0 and later. The default value
       is backwards compatible with Postfix 1.1.

       The default value is $virtual_alias_maps  so  that  you  can  keep  all
       information about virtual alias domains in one place.  If you have many
       users,  it  is  better  to  separate  information  that  changes   more
       frequently  (virtual  address  -> local or remote address mapping) from
       information that changes less frequently (the list  of  virtual  domain
       names).

       Specify  a  list  of host or domain names, "/file/name" or "type:table"
       patterns, separated by commas and/or whitespace. A "/file/name" pattern
       is  replaced  by  its  contents; a "type:table" lookup table is matched
       when a table entry matches  a  lookup  string  (the  lookup  result  is
       ignored).    Continue  long  lines  by  starting  the  next  line  with
       whitespace.

       See also the  VIRTUAL_README  and  ADDRESS_CLASS_README  documents  for
       further information.

       Example:

       virtual_alias_domains = virtual1.tld virtual2.tld

virtual_alias_expansion_limit (default: 1000)

       The  maximal  number of addresses that virtual alias expansion produces
       from each original recipient.

       This feature is available in Postfix 2.1 and later.

virtual_alias_maps (default: $virtual_maps)

       Optional lookup tables that alias specific mail addresses or domains to
       other  local  or  remote  address.   The  table  format and lookups are
       documented  in  virtual(5).  For  an  overview   of   Postfix   address
       manipulations see the ADDRESS_REWRITING_README document.

       This  feature  is available in Postfix 2.0 and later. The default value
       is backwards compatible with Postfix 1.1.

       If  you  use  this   feature   with   indexed   files,   run   "postmap
       /etc/postfix/virtual" after changing the file.

       Examples:

       virtual_alias_maps = dbm:/etc/postfix/virtual
       virtual_alias_maps = hash:/etc/postfix/virtual

virtual_alias_recursion_limit (default: 1000)

       The  maximal  nesting  depth of virtual alias expansion.  Currently the
       recursion limit is applied only to the left  branch  of  the  expansion
       graph,  so the depth of the tree can in the worst case reach the sum of
       the expansion and recursion limits.  This may change in the future.

       This feature is available in Postfix 2.1 and later.

virtual_destination_concurrency_limit (default:

       $default_destination_concurrency_limit)
       The  maximal  number of parallel deliveries to the same destination via
       the virtual message delivery transport. This limit is enforced  by  the
       queue  manager.  The message delivery transport name is the first field
       in the entry in the master.cf file.

virtual_destination_recipient_limit (default:

       $default_destination_recipient_limit)
       The  maximal  number of recipients per delivery via the virtual message
       delivery transport. This limit is enforced by the  queue  manager.  The
       message  delivery transport name is the first field in the entry in the
       master.cf file.

       Setting this  parameter  to  a  value  of  1  changes  the  meaning  of
       virtual_destination_concurrency_limit  from concurrency per domain into
       concurrency per recipient.

virtual_gid_maps (default: empty)

       Lookup tables with the per-recipient group ID  for  virtual(8)  mailbox
       delivery.

       In  a  lookup table, specify a left-hand side of "@domain.tld" to match
       any user in  the  specified  domain  that  does  not  have  a  specific
       "user@domain.tld" entry.

       When   a   recipient   address   has   an  optional  address  extension
       (user+foo@domain.tld), the virtual(8) delivery agent looks up the  full
       address  first,  and  when the lookup fails, it looks up the unextended
       address (user@domain.tld).

       Note 1: for security reasons, the virtual(8) delivery  agent  disallows
       regular expression substitution of $1 etc. in regular expression lookup
       tables, because that would open a security hole.

       Note 2: for  security  reasons,  the  virtual(8)  delivery  agent  will
       silently ignore requests to use the proxymap(8) server. Instead it will
       open the table directly. Before Postfix  version  2.2,  the  virtual(8)
       delivery agent will terminate with a fatal error.

virtual_mailbox_base (default: empty)

       A  prefix  that  the virtual(8) delivery agent prepends to all pathname
       results from $virtual_mailbox_maps table lookups.   This  is  a  safety
       measure  to  ensure  that an out of control map doesn’t litter the file
       system with mailboxes.  While virtual_mailbox_base could be set to "/",
       this setting isn’t recommended.

       Example:

       virtual_mailbox_base = /var/mail

virtual_mailbox_domains (default: $virtual_mailbox_maps)

       Postfix is final destination for the specified list of domains; mail is
       delivered via  the  $virtual_transport  mail  delivery  transport.   By
       default this is the Postfix virtual(8) delivery agent.  The SMTP server
       validates recipient addresses with  $virtual_mailbox_maps  and  rejects
       mail  for non-existent recipients.  See also the virtual mailbox domain
       class in the ADDRESS_CLASS_README file.

       This  parameter  expects  the  same   syntax   as   the   mydestination
       configuration parameter.

       This  feature  is available in Postfix 2.0 and later. The default value
       is backwards compatible with Postfix 1.1.

virtual_mailbox_limit (default: 51200000)

       The maximal size in bytes of an individual mailbox or maildir file,  or
       zero (no limit).

virtual_mailbox_lock (default: see postconf -d output)

       How to lock a UNIX-style virtual(8) mailbox before attempting delivery.
       For a list of available file locking methods,  use  the  "postconf  -l"
       command.

       This  setting  is  ignored  with  maildir  style delivery, because such
       deliveries are safe without application-level locks.

       Note 1: the dotlock method requires that the recipient UID or  GID  has
       write access to the parent directory of the recipient’s mailbox file.

       Note 2: the default setting of this parameter is system dependent.

virtual_mailbox_maps (default: empty)

       Optional  lookup  tables  with  all valid addresses in the domains that
       match $virtual_mailbox_domains.

       In a lookup table, specify a left-hand side of "@domain.tld"  to  match
       any  user  in  the  specified  domain  that  does  not  have a specific
       "user@domain.tld" entry.

       The virtual(8) delivery agent uses this  table  to  look  up  the  per-
       recipient  mailbox or maildir pathname.  If the lookup result ends in a
       slash ("/"), maildir-style delivery is carried out, otherwise the  path
       is   assumed   to   specify  a  UNIX-style  mailbox  file.   Note  that
       $virtual_mailbox_base is unconditionally prepended to this path.

       When  a  recipient  address   has   an   optional   address   extension
       (user+foo@domain.tld),  the virtual(8) delivery agent looks up the full
       address first, and when the lookup fails, it looks  up  the  unextended
       address (user@domain.tld).

       Note  1:  for security reasons, the virtual(8) delivery agent disallows
       regular expression substitution of $1 etc. in regular expression lookup
       tables, because that would open a security hole.

       Note  2:  for  security  reasons,  the  virtual(8)  delivery agent will
       silently ignore requests to use the proxymap(8) server. Instead it will
       open  the  table  directly.  Before Postfix version 2.2, the virtual(8)
       delivery agent will terminate with a fatal error.

virtual_maps (default: empty)

       Optional lookup tables with a) names of domains for which all addresses
       are  aliased  to  addresses  in  other  local or remote domains, and b)
       addresses that are aliased  to  addresses  in  other  local  or  remote
       domains.   Available  before  Postfix version 2.0. With Postfix 2.0 and
       later, this is replaced by separate controls: virtual_alias_domains and
       virtual_alias_maps.

virtual_minimum_uid (default: 100)

       The minimum user ID value that the virtual(8) delivery agent accepts as
       a result from $virtual_uid_maps table  lookup.   Returned  values  less
       than this will be rejected, and the message will be deferred.

virtual_transport (default: virtual)

       The  default  mail  delivery  transport  for  domains  that  match  the
       $virtual_mailbox_domains  parameter  value.  This  information  can  be
       overruled with the transport(5) table.

       Specify  a string of the form transport:nexthop, where transport is the
       name of a mail delivery transport defined in master.cf.   The  :nexthop
       part is optional.  For more details see the transport(5) manual page.

       This feature is available in Postfix 2.0 and later.

virtual_uid_maps (default: empty)

       Lookup  tables  with  the  per-recipient  user  ID  that the virtual(8)
       delivery agent uses while writing to the recipient’s mailbox.

       In a lookup table, specify a left-hand side of "@domain.tld"  to  match
       any  user  in  the  specified  domain  that  does  not  have a specific
       "user@domain.tld" entry.

       When  a  recipient  address   has   an   optional   address   extension
       (user+foo@domain.tld),  the virtual(8) delivery agent looks up the full
       address first, and when the lookup fails, it looks  up  the  unextended
       address (user@domain.tld).

       Note  1:  for security reasons, the virtual(8) delivery agent disallows
       regular expression substitution of $1 etc. in regular expression lookup
       tables, because that would open a security hole.

       Note  2:  for  security  reasons,  the  virtual(8)  delivery agent will
       silently ignore requests to use the proxymap(8) server. Instead it will
       open  the  table  directly.  Before Postfix version 2.2, the virtual(8)
       delivery agent will terminate with a fatal error.

SEE ALSO

       postconf(1), Postfix configuration parameter maintenance
       master(5), Postfix daemon configuration maintenance

LICENSE

       The Secure Mailer license must be distributed with this software.

AUTHOR(S)

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

                                                                   POSTCONF(5)