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Linux 2.6 - man page for virtual (linux section 8postfix)

VIRTUAL(8postfix)								VIRTUAL(8postfix)

       virtual - Postfix virtual domain mail delivery agent

       virtual [generic Postfix daemon options]

       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.

       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:


       where recipient is the full recipient address.

       When the mailbox location does not end in /, the message is delivered in UNIX mailbox for-
       mat.   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 prob-
       lems, an attempt is made to truncate the mailbox to its original length.

       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 enve-
       lope 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

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

       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.

       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.

       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.

       o      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.

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

       o      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.

       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 reg-
       ular 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.

       RFC 822 (ARPA Internet Text Messages)

       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).  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.

       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.

       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 includ-
       ing examples.

       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  $vir-

	      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.

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

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

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

	      The time after which a stale exclusive mailbox lockfile is removed.

       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

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

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

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

	      The  maximal number of digits after the decimal point when logging sub-second delay

	      The time limit for sending or receiving information over an internal  communication

	      The  maximum amount of time that an idle Postfix daemon process waits for an incom-
	      ing connection before terminating voluntarily.

	      The maximal number of incoming connections that a Postfix daemon process will  ser-
	      vice 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)
	      The  mail  system  name that is prepended to the process name in syslog records, so
	      that "smtpd" becomes, for example, "postfix/smtpd".

       qmgr(8), queue manager
       bounce(8), delivery status reports
       postconf(5), configuration parameters
       syslogd(8), system logging

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

       The Secure Mailer license must be distributed with this software.

       This delivery agent was originally based on the Postfix local  delivery	agent.	Modifica-
       tions  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

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

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

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

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


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