Ubuntu Manpage: virtual - Postfix virtual domain mail delivery agent

Provided by: postfix_3.4.13-0ubuntu1.4_amd64

NAME

       virtual - Postfix virtual domain mail delivery agent

SYNOPSIS

       virtual [generic Postfix daemon options]

DESCRIPTION

       The  virtual(8)  delivery  agent  is  designed for virtual mail hosting services. Originally based on the
       Postfix local(8) delivery agent, this agent looks up recipients with map lookups of their full  recipient
       address, instead of using hard-coded unix password file lookups of the address local part only.

       This  delivery  agent  only  delivers  mail.   Other  features  such  as  mail  forwarding, out-of-office
       notifications, etc., must be configured via virtual_alias maps or via similar lookup mechanisms.

MAILBOX LOCATION

       The mailbox location is controlled by the  virtual_mailbox_base  and  virtual_mailbox_maps  configuration
       parameters  (see below).  The virtual_mailbox_maps table is indexed by the recipient address as described
       under TABLE SEARCH ORDER below.

       The mailbox pathname is constructed as follows:

         $virtual_mailbox_base/$virtual_mailbox_maps(recipient)

       where recipient is the full recipient address.

UNIX MAILBOX FORMAT

       When the mailbox location does not end in /, the message is delivered  in  UNIX  mailbox  format.    This
       format stores multiple messages in one textfile.

       The  virtual(8)  delivery  agent  prepends  a  "From  sender time_stamp" envelope header to each message,
       prepends a Delivered-To: message header with the envelope recipient address, prepends  an  X-Original-To:
       header  with  the  recipient address as given to Postfix, prepends a Return-Path: message header with the
       envelope sender address, prepends a > character to lines beginning with "From ",  and  appends  an  empty
       line.

       The mailbox is locked for exclusive access while delivery is in progress. In case of problems, an attempt
       is made to truncate the mailbox to its original length.

QMAIL MAILDIR FORMAT

       When the mailbox location ends in /, the message is delivered in qmail maildir format. This format stores
       one message per file.

       The  virtual(8)  delivery agent prepends a Delivered-To: message header with the final envelope recipient
       address, prepends an X-Original-To: header with the recipient address as given to Postfix, and prepends a
       Return-Path: message header with the envelope sender address.

       By  definition,  maildir  format  does not require application-level file locking during mail delivery or
       retrieval.

MAILBOX OWNERSHIP

       Mailbox ownership is controlled by the virtual_uid_maps and virtual_gid_maps  lookup  tables,  which  are
       indexed  with  the full recipient address. Each table provides a string with the numerical user and group
       ID, respectively.

       The virtual_minimum_uid parameter imposes a lower bound on numerical user ID values that may be specified
       in any virtual_uid_maps.

CASE FOLDING

       All delivery decisions are made using the full recipient address, folded to lower case. See also the next
       section for a few exceptions with optional address extensions.

TABLE SEARCH ORDER

       Normally, a lookup 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.

       The search order is as follows. The search stops upon the first successful lookup.

       •      When  the  recipient  has  an  optional address extension the user+extension@domain.tld address is
              looked up first.

              With Postfix versions before 2.1, the optional address extension is always ignored.

       •      The user@domain.tld address, without address extension, is looked up next.

       •      Finally, the recipient @domain is looked up.

       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,  a  table  can be provided as a regular-expression map where patterns are given as regular
       expressions. In that case, only the full recipient address is given to the regular-expression map.

SECURITY

       The virtual(8) delivery agent is not security sensitive, provided that the lookup tables  with  recipient
       user/group ID information are adequately protected. This program is not designed to run chrooted.

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

       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 delivery agent will terminate with
       a fatal error.

STANDARDS

       RFC 822 (ARPA Internet Text Messages)

DIAGNOSTICS

       Mail bounces when the recipient has no mailbox or when the recipient is over disk  quota.  In  all  other
       cases, mail for an existing recipient is deferred and a warning is logged.

       Problems and transactions are logged to syslogd(8) or postlogd(8).  Corrupted message files are marked so
       that the queue manager can move them to the corrupt queue afterwards.

       Depending on the setting of the notify_classes parameter, the postmaster is notified of  bounces  and  of
       other trouble.

BUGS

       This delivery agent supports address extensions in email addresses and in lookup table keys, but does not
       propagate address extension information to the result of table lookup.

       Postfix should have lookup tables that can return multiple result  attributes.  In  order  to  avoid  the
       inconvenience of maintaining three tables, use an LDAP or MYSQL database.

CONFIGURATION PARAMETERS

       Changes  to main.cf are picked up automatically, as virtual(8) processes run for only a limited amount of
       time. Use the command "postfix reload" to speed up a change.

       The text below provides only a parameter summary. See postconf(5) for more details including examples.

MAILBOX DELIVERY CONTROLS

       virtual_mailbox_base (empty)
              A  prefix  that  the  virtual(8)  delivery  agent  prepends   to   all   pathname   results   from
              $virtual_mailbox_maps table lookups.

       virtual_mailbox_maps (empty)
              Optional    lookup    tables    with   all   valid   addresses   in   the   domains   that   match
              $virtual_mailbox_domains.

       virtual_minimum_uid (100)
              The minimum  user  ID  value  that  the  virtual(8)  delivery  agent  accepts  as  a  result  from
              $virtual_uid_maps table lookup.

       virtual_uid_maps (empty)
              Lookup tables with the per-recipient user ID that the virtual(8) delivery agent uses while writing
              to the recipient's mailbox.

       virtual_gid_maps (empty)
              Lookup tables with the per-recipient group ID for virtual(8) mailbox delivery.

       Available in Postfix version 2.0 and later:

       virtual_mailbox_domains ($virtual_mailbox_maps)
              Postfix is final destination for the  specified  list  of  domains;  mail  is  delivered  via  the
              $virtual_transport mail delivery transport.

       virtual_transport (virtual)
              The  default mail delivery transport and next-hop destination for final delivery to domains listed
              with $virtual_mailbox_domains.

       Available in Postfix version 2.5.3 and later:

       strict_mailbox_ownership (yes)
              Defer delivery when a mailbox file is not owned by its recipient.

LOCKING CONTROLS

       virtual_mailbox_lock (see 'postconf -d' output)
              How to lock a UNIX-style virtual(8) mailbox before attempting delivery.

       deliver_lock_attempts (20)
              The maximal number of attempts to acquire an  exclusive  lock  on  a  mailbox  file  or  bounce(8)
              logfile.

       deliver_lock_delay (1s)
              The time between attempts to acquire an exclusive lock on a mailbox file or bounce(8) logfile.

       stale_lock_time (500s)
              The time after which a stale exclusive mailbox lockfile is removed.

RESOURCE AND RATE CONTROLS

       virtual_mailbox_limit (51200000)
              The maximal size in bytes of an individual virtual(8) mailbox or maildir file, or zero (no limit).

       Implemented in the qmgr(8) daemon:

       virtual_destination_concurrency_limit ($default_destination_concurrency_limit)
              The maximal number of parallel deliveries to the same destination via the virtual message delivery
              transport.

       virtual_destination_recipient_limit ($default_destination_recipient_limit)
              The maximal number of recipients per message for the virtual message delivery transport.

MISCELLANEOUS CONTROLS

config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf configuration files.

daemon_timeout (18000s)
How much time a Postfix daemon process may take to handle a request before it is terminated by a
built-in watchdog timer.

delay_logging_resolution_limit (2)
The maximal number of digits after the decimal point when logging sub-second delay values.

ipc_timeout (3600s)
The time limit for sending or receiving information over an internal communication channel.

max_idle (100s)
The maximum amount of time that an idle Postfix daemon process waits for an incoming connection
before terminating voluntarily.

max_use (100)
The maximal number of incoming connections that a Postfix daemon process will service before
terminating voluntarily.

process_id (read-only)
The process ID of a Postfix command or daemon process.

process_name (read-only)
The process name of a Postfix command or daemon process.

queue_directory (see 'postconf -d' output)
The location of the Postfix top-level queue directory.

syslog_facility (mail)
The syslog facility of Postfix logging.

syslog_name (see 'postconf -d' output)
A prefix that is prepended to the process name in syslog records, so that, for example, "smtpd"
becomes "prefix/smtpd".

Available in Postfix version 3.0 and later:

virtual_delivery_status_filter ($default_delivery_status_filter)
Optional filter for the virtual(8) delivery agent to change the delivery status code or
explanatory text of successful or unsuccessful deliveries.

Available in Postfix version 3.3 and later:

enable_original_recipient (yes)
Enable support for the original recipient address after an address is rewritten to a different
address (for example with aliasing or with canonical mapping).

service_name (read-only)
The master.cf service name of a Postfix daemon process.

README_FILES

       Use "postconf readme_directory" or
       "postconf html_directory" to locate this information.
       VIRTUAL_README, domain hosting howto

LICENSE

       The Secure Mailer license must be distributed with this software.

HISTORY

       This delivery agent was originally based on  the  Postfix  local  delivery  agent.  Modifications  mainly
       consisted  of removing code that either was not applicable or that was not safe in this context: aliases,
       ~user/.forward files, delivery to "|command" or to /file/name.

       The Delivered-To: message header appears in the qmail system by Daniel Bernstein.

       The maildir structure appears in the qmail system by Daniel Bernstein.

AUTHOR(S)

       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

       Andrew McNamara
       andrewm@connect.com.au
       connect.com.au Pty. Ltd.
       Level 3, 213 Miller St
       North Sydney 2060, NSW, Australia

                                                                                               VIRTUAL(8postfix)