Provided by: postfix_2.7.0-1_i386 bug

NAME

       access - Postfix SMTP server access table

SYNOPSIS

       postmap /etc/postfix/access

       postmap -q "string" /etc/postfix/access

       postmap -q - /etc/postfix/access <inputfile

DESCRIPTION

       This   document   describes   access  control  on  remote  SMTP  client
       information: host names, network  addresses,  and  envelope  sender  or
       recipient addresses; it is implemented by the Postfix SMTP server.  See
       header_checks(5) or body_checks(5) for access control on the content of
       email messages.

       Normally,  the  access(5) table is specified as a text file that serves
       as input to the postmap(1) command.  The result, an indexed file in dbm
       or  db  format,  is used for fast searching by the mail system. Execute
       the command "postmap /etc/postfix/access" to rebuild  an  indexed  file
       after changing the corresponding text file.

       When  the  table  is provided via other means such as NIS, LDAP or SQL,
       the same lookups are done as for ordinary indexed files.

       Alternatively, the table can be provided as  a  regular-expression  map
       where  patterns  are  given  as  regular expressions, or lookups can be
       directed to TCP-based server. In those cases, the lookups are done in a
       slightly  different  way  as  described below under "REGULAR EXPRESSION
       TABLES" or "TCP-BASED TABLES".

CASE FOLDING

       The search string is folded to lowercase before database lookup. As  of
       Postfix  2.3,  the search string is not case folded with database types
       such as regexp: or pcre: whose lookup fields can match both  upper  and
       lower case.

TABLE FORMAT

       The input format for the postmap(1) command is as follows:

       pattern action
              When  pattern  matches  a  mail address, domain or host address,
              perform the corresponding action.

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

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

EMAIL ADDRESS PATTERNS

       With lookups from indexed files such as DB or DBM,  or  from  networked
       tables  such  as  NIS,  LDAP or SQL, patterns are tried in the order as
       listed below:

       user@domain
              Matches the specified mail address.

       domain.tld
              Matches domain.tld as the domain part of an email address.

              The pattern domain.tld also matches subdomains,  but  only  when
              the   string   smtpd_access_maps   is   listed  in  the  Postfix
              parent_domain_matches_subdomains  configuration  setting   (note
              that  this  is  the  default  for  some  versions  of  Postfix).
              Otherwise, specify .domain.tld (note the initial dot)  in  order
              to match subdomains.

       user@  Matches all mail addresses with the specified user part.

       Note: lookup of the null sender address is not possible with some types
       of lookup table. By default, Postfix uses <> as the lookup key for such
       addresses. The value is specified with the smtpd_null_access_lookup_key
       parameter in the Postfix main.cf file.

EMAIL ADDRESS EXTENSION

       When a mail address localpart contains the optional recipient delimiter
       (e.g.,  user+foo@domain),  the  lookup  order becomes: user+foo@domain,
       user@domain, domain, user+foo@, and user@.

HOST NAME/ADDRESS PATTERNS

       With lookups from indexed files such as DB or DBM,  or  from  networked
       tables  such  as  NIS,  LDAP  or SQL, the following lookup patterns are
       examined in the order as listed:

       domain.tld
              Matches domain.tld.

              The pattern domain.tld also matches subdomains,  but  only  when
              the   string   smtpd_access_maps   is   listed  in  the  Postfix
              parent_domain_matches_subdomains     configuration      setting.
              Otherwise,  specify  .domain.tld (note the initial dot) in order
              to match subdomains.

       net.work.addr.ess

       net.work.addr

       net.work

       net    Matches the specified IPv4 host address or subnetwork.  An  IPv4
              host  address  is a sequence of four decimal octets separated by
              ".".

              Subnetworks  are  matched  by  repeatedly  truncating  the  last
              ".octet"  from the remote IPv4 host address string until a match
              is found in the access table, or until further truncation is not
              possible.

              NOTE  1: The access map lookup key must be in canonical form: do
              not specify unnecessary null  characters,  and  do  not  enclose
              network address information with "[]" characters.

              NOTE   2:   use   the   cidr   lookup   table  type  to  specify
              network/netmask patterns. See cidr_table(5) for details.

       net:work:addr:ess

       net:work:addr

       net:work

       net    Matches the specified IPv6 host address or subnetwork.  An  IPv6
              host  address  is a sequence of three to eight hexadecimal octet
              pairs separated by ":".

              Subnetworks  are  matched  by  repeatedly  truncating  the  last
              ":octetpair"  from  the  remote IPv6 host address string until a
              match is found in the access table, or until further  truncation
              is not possible.

              NOTE  1:  the truncation and comparison are done with the string
              representation of the IPv6 host address. Thus, not all  the  ":"
              subnetworks will be tried.

              NOTE  2: The access map lookup key must be in canonical form: do
              not specify unnecessary null  characters,  and  do  not  enclose
              network address information with "[]" characters.

              NOTE   3:   use   the   cidr   lookup   table  type  to  specify
              network/netmask patterns. See cidr_table(5) for details.

              IPv6 support is available in Postfix 2.2 and later.

ACCEPT ACTIONS

       OK     Accept the address etc. that matches the pattern.

       all-numerical
              An all-numerical  result  is  treated  as  OK.  This  format  is
              generated  by  address-based relay authorization schemes such as
              pop-before-smtp.

REJECT ACTIONS

       Postfix version 2.3 and later support enhanced status codes as  defined
       in  RFC  3463.   When no code is specified at the beginning of the text
       below, Postfix inserts a default enhanced status code of "5.7.1" in the
       case  of  reject actions, and "4.7.1" in the case of defer actions. See
       "ENHANCED STATUS CODES" below.

       4NN text

       5NN text
              Reject the address etc. that matches the  pattern,  and  respond
              with  the  numerical  three-digit  code and text. 4NN means "try
              again later", while 5NN means "do not try again".

              The following responses have special  meaning  for  the  Postfix
              SMTP server:

              421 text (Postfix 2.3 and later)

              521 text (Postfix 2.6 and later)
                     After  responding with the numerical three-digit code and
                     text, disconnect immediately from the SMTP client.   This
                     frees  up  SMTP server resources so that they can be made
                     available to another SMTP client.

                     Note: The "521" response should be used only with botnets
                     and   other  malware  where  interoperability  is  of  no
                     concern.  The "send 521 and disconnect" behavior  is  NOT
                     defined in the SMTP standard.

       REJECT optional text...
              Reject  the  address  etc.  that matches the pattern. Reply with
              "$access_map_reject_code optional  text..."  when  the  optional
              text is specified, otherwise reply with a generic error response
              message.

       DEFER optional text...
              Reject the address etc. that matches  the  pattern.  Reply  with
              "$access_map_defer_code optional text..." when the optional text
              is specified, otherwise reply  with  a  generic  error  response
              message.

              This feature is available in Postfix 2.6 and later.

       DEFER_IF_REJECT optional text...
              Defer  the  request  if some later restriction would result in a
              REJECT action. Reply with "$access_map_defer_code 4.7.1 optional
              text..."  when  the  optional text is specified, otherwise reply
              with a generic error response message.

              Prior to Postfix 2.6, the SMTP reply code is 450.

              This feature is available in Postfix 2.1 and later.

       DEFER_IF_PERMIT optional text...
              Defer the request if some later restriction would result in a an
              explicit    or    implicit    PERMIT    action.     Reply   with
              "$access_map_defer_code  4.7.1   optional  text..."   when   the
              optional text is specified, otherwise reply with a generic error
              response message.

              Prior to Postfix 2.6, the SMTP reply code is 450.

              This feature is available in Postfix 2.1 and later.

OTHER ACTIONS

       restriction...
              Apply   the   named   UCE   restriction(s)   (permit,    reject,
              reject_unauth_destination, and so on).

       BCC user@domain
              Send one copy of the message to the specified recipient.

              If  multiple BCC actions are specified within the same SMTP MAIL
              transaction, only the last action will be used.

              This feature is not part of the stable Postfix release.

       DISCARD optional text...
              Claim successful delivery and silently discard the message.  Log
              the optional text if specified, otherwise log a generic message.

              Note: this  action  currently  affects  all  recipients  of  the
              message.   To  discard only one recipient without discarding the
              entire message, use the transport(5) table to direct mail to the
              discard(8) service.

              This feature is available in Postfix 2.0 and later.

       DUNNO  Pretend that the lookup key was not found. This prevents Postfix
              from trying substrings of the lookup key (such  as  a  subdomain
              name, or a network address subnetwork).

              This feature is available in Postfix 2.0 and later.

       FILTER transport:destination
              After the message is queued, send the entire message through the
              specified external content filter. The transport name  specifies
              the   first  field  of  a  mail  delivery  agent  definition  in
              master.cf; the syntax of the next-hop destination  is  described
              in  the  manual  page of the corresponding delivery agent.  More
              information about external content filters  is  in  the  Postfix
              FILTER_README file.

              Note  1: do not use $number regular expression substitutions for
              transport or destination unless you know  that  the  information
              has a trusted origin.

              Note   2:  this  action  overrides  the  main.cf  content_filter
              setting, and affects all recipients of the message. In the  case
              that  multiple  FILTER  actions  fire,  only  the  last  one  is
              executed.

              Note 3: the purpose of the FILTER command is to override message
              routing.   To  override  the  recipient’s  transport but not the
              next-hop  destination,  specify  an  empty  filter   destination
              (Postfix 2.7 and later), or specify a transport:destination that
              delivers through a different Postfix instance (Postfix  2.6  and
              earlier). Other options are using the recipient-dependent transport_maps  or  the  sender-dependent   sender_dependent_default_transport_maps features.

              This feature is available in Postfix 2.0 and later.

       HOLD optional text...
              Place  the  message  on  the hold queue, where it will sit until
              someone either deletes it or releases it for delivery.  Log  the
              optional text if specified, otherwise log a generic message.

              Mail  that is placed on hold can be examined with the postcat(1)
              command, and can be destroyed or released with the  postsuper(1)
              command.

              Note:  use  "postsuper -r" to release mail that was kept on hold
              for  a  significant  fraction  of   $maximal_queue_lifetime   or
              $bounce_queue_lifetime,  or  longer. Use "postsuper -H" only for
              mail that will not expire within a few delivery attempts.

              Note: this  action  currently  affects  all  recipients  of  the
              message.

              This feature is available in Postfix 2.0 and later.

       PREPEND headername: headervalue
              Prepend  the specified message header to the message.  When more
              than one PREPEND action executes,  the  first  prepended  header
              appears before the second etc. prepended header.

              Note:  this  action  must  execute before the message content is
              received;   it   cannot    execute    in    the    context    of
              smtpd_end_of_data_restrictions.

              This feature is available in Postfix 2.1 and later.

       REDIRECT user@domain
              After  the  message is queued, send the message to the specified
              address instead of the intended recipient(s).

              Note: this action overrides the  FILTER  action,  and  currently
              affects all recipients of the message.

              This feature is available in Postfix 2.1 and later.

       WARN optional text...
              Log  a  warning  with  the  optional  text, together with client
              information and if available, with helo, sender,  recipient  and
              protocol information.

              This feature is available in Postfix 2.1 and later.

ENHANCED STATUS CODES

       Postfix  version 2.3 and later support enhanced status codes as defined
       in RFC 3463.  When an enhanced status code is specified  in  an  access
       table, it is subject to modification. The following transformations are
       needed when the same access table is used for client, helo, sender,  or
       recipient  access  restrictions;  they  happen  regardless  of  whether
       Postfix replies to a MAIL FROM, RCPT TO or other SMTP command.

       ·      When a sender address matches a REJECT action, the Postfix  SMTP
              server will transform a recipient DSN status (e.g., 4.1.1-4.1.6)
              into the corresponding sender DSN status, and vice versa.

       ·      When non-address information matches a REJECT  action  (such  as
              the  HELO  command argument or the client hostname/address), the
              Postfix SMTP server will transform a  sender  or  recipient  DSN
              status into a generic non-address DSN status (e.g., 4.0.0).

REGULAR EXPRESSION TABLES

       This  section  describes how the table lookups change when the table is
       given in the form of regular expressions. For a description of  regular
       expression lookup table syntax, see regexp_table(5) or pcre_table(5).

       Each  pattern  is  a  regular  expression that is applied to the entire
       string being looked up. Depending on the application, that string is an
       entire  client hostname, an entire client IP address, or an entire mail
       address. Thus, no parent domain  or  parent  network  search  is  done,
       user@domain  mail  addresses  are  not  broken  up into their user@ and
       domain constituent parts, nor is user+foo broken up into user and  foo.

       Patterns  are  applied  in the order as specified in the table, until a
       pattern is found that matches the search string.

       Actions are the same as with indexed file lookups, with the  additional
       feature   that   parenthesized  substrings  from  the  pattern  can  be
       interpolated as $1, $2 and so on.

TCP-BASED TABLES

       This section describes how the table lookups change  when  lookups  are
       directed   to  a  TCP-based  server.  For  a  description  of  the  TCP
       client/server lookup protocol, see tcp_table(5).  This feature  is  not
       available up to and including Postfix version 2.4.

       Each  lookup operation uses the entire query string once.  Depending on
       the application, that string is an entire client  hostname,  an  entire
       client  IP  address, or an entire mail address.  Thus, no parent domain
       or parent network search is done, user@domain mail  addresses  are  not
       broken  up  into  their  user@  and  domain  constituent  parts, nor is
       user+foo broken up into user and foo.

       Actions are the same as with indexed file lookups.

EXAMPLE

       The following example uses an indexed file, so that the order of  table
       entries  does  not  matter. The example permits access by the client at
       address 1.2.3.4 but rejects all other clients in 1.2.3.0/24. Instead of
       hash  lookup  tables,  some systems use dbm.  Use the command "postconf
       -m" to find out what lookup tables Postfix supports on your system.

       /etc/postfix/main.cf:
           smtpd_client_restrictions =
               check_client_access hash:/etc/postfix/access

       /etc/postfix/access:
           1.2.3   REJECT
           1.2.3.4 OK

       Execute the command "postmap  /etc/postfix/access"  after  editing  the
       file.

BUGS

       The table format does not understand quoting conventions.

SEE ALSO

       postmap(1), Postfix lookup table manager
       smtpd(8), SMTP server
       postconf(5), configuration parameters
       transport(5), transport:nexthop syntax

README FILES

       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       SMTPD_ACCESS_README, built-in SMTP server access control
       DATABASE_README, Postfix lookup table overview

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

                                                                     ACCESS(5)