Provided by: postfix_2.2.10-1_i386 bug

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.

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).  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 for domains that  match  the
              $virtual_mailbox_domains parameter value.

LOCKING CONTROLS

       virtual_mailbox_lock (seepostconf -doutput)
              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_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 delivery  via  the  virtual
              message delivery transport.

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

MISCELLANEOUS CONTROLS

       config_directory (seepostconf -doutput)
              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.

       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 the next service request before exiting.

       max_use (100)
              The maximal number  of  connection  requests  before  a  Postfix
              daemon process terminates.

       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 (seepostconf -doutput)
              The location of the Postfix top-level queue directory.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (postfix)
              The  mail  system  name that is prepended to the process name in
              syslog  records,  so  that   "smtpd"   becomes,   for   example,
              "postfix/smtpd".

SEE ALSO

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

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

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

                                                                    VIRTUAL(8)