Provided by: postfix_2.2.10-1_i386 bug

NAME

       virtual - Postfix virtual alias table format

SYNOPSIS

       postmap /etc/postfix/virtual

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

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

DESCRIPTION

       The  optional  virtual(5)  alias table rewrites recipient addresses for
       all local, virtual and remote mail destinations.  This  is  unlike  the
       aliases(5)  table  which  is  used only for local(8) delivery.  Virtual
       aliasing is recursive, and is implemented  by  the  Postfix  cleanup(8)
       daemon before mail is queued.

       The main applications of virtual aliasing are:

       ·      To redirect mail for one address to one or more addresses.

       ·      To  implement  virtual  alias  domains  where  all addresses are
              aliased to addresses in other domains.

              Virtual alias domains are not to be confused  with  the  virtual
              mailbox domains that are implemented with the Postfix virtual(8)
              mail  delivery  agent.  With  virtual  mailbox   domains,   each
              recipient address can have its own mailbox.

       Virtual  aliasing  is applied only to recipient envelope addresses, and
       does not affect message headers.  Think Sendmail rule set  S0,  if  you
       like. Use canonical(5) mapping to rewrite header and envelope addresses
       in general.

       Normally, the virtual(5) alias 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/virtual" in order to rebuild
       the indexed file after changing the 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 that case, the lookups are done in a
       slightly different way as described  below  under  "REGULAR  EXPRESSION
       TABLES" and "TCP-BASED TABLES".

TABLE FORMAT

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

       pattern result
              When   pattern  matches  a  mail  address,  replace  it  by  the
              corresponding result.

       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.

TABLE SEARCH ORDER

       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 address, address, ...
              Redirect mail for user@domain to address.   This  form  has  the
              highest precedence.

       user address, address, ...
              Redirect  mail  for  user@site  to address when site is equal to
              $myorigin, when site is listed in $mydestination, or when it  is
              listed in $inet_interfaces or $proxy_interfaces.

              This  functionality  overlaps  with  functionality  of the local
              aliases(5) database. The difference is that  virtual(5)  mapping
              can be applied to non-local addresses.

       @domain address, address, ...
              Redirect  mail  for other users in domain to address.  This form
              has the lowest precedence.

RESULT ADDRESS REWRITING

       The lookup result is subject to address rewriting:

       ·      When the result has the form @otherdomain,  the  result  becomes
              the  same  user  in  otherdomain.  This works only for the first
              address in a multi-address lookup result.

       ·      When "append_at_myorigin=yes", append "@$myorigin" to  addresses
              without "@domain".

       ·      When "append_dot_mydomain=yes", append ".$mydomain" to addresses
              without ".domain".

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, user+foo, user, and @domain.

       The  propagate_unmatched_extensions  parameter  controls   whether   an
       unmatched address extension (+foo) is propagated to the result of table
       lookup.

VIRTUAL ALIAS DOMAINS

       Besides virtual aliases, the virtual alias table can also  be  used  to
       implement  virtual  alias  domains.  With  a  virtual alias domain, all
       recipient addresses are aliased to addresses in other domains.

       Virtual alias domains are not to be confused with the  virtual  mailbox
       domains  that are implemented with the Postfix virtual(8) mail delivery
       agent. With virtual mailbox domains, each recipient  address  can  have
       its own mailbox.

       With  a  virtual alias domain, the virtual domain has its own user name
       space. Local (i.e. non-virtual) usernames are not visible in a  virtual
       alias  domain.  In particular, local aliases(5) and local mailing lists
       are not visible as localname@virtual-alias.domain.

       Support for a virtual alias domain looks like:

       /etc/postfix/main.cf:
           virtual_alias_maps = hash:/etc/postfix/virtual

           Note: some systems use dbm databases  instead  of  hash.   See  the
           output from "postconf -m" for available database types.

       /etc/postfix/virtual:
           virtual-alias.domain anything (right-hand content does not matter)
           postmaster@virtual-alias.domain      postmaster
           user1@virtual-alias.domain   address1
           user2@virtual-alias.domain   address2, address3

       The virtual-alias.domain anything entry is required for a virtual alias
       domain. Without  this  entry,  mail  is  rejected  with  "relay  access
       denied", or bounces with "mail loops back to myself".

       Do  not specify virtual alias domain names in the main.cf mydestination
       or relay_domains configuration parameters.

       With a virtual alias domain, the Postfix SMTP server accepts  mail  for
       known-user@virtual-alias.domain,   and   rejects   mail   for  unknown-
       user@virtual-alias.domain as undeliverable.

       Instead  of  specifying  the  virtual  alias  domain   name   via   the
       virtual_alias_maps  table,  you  may  also  specify  it via the main.cf
       virtual_alias_domains configuration parameter.  This  latter  parameter
       uses  the  same  syntax  as  the  main.cf  mydestination  configuration
       parameter.

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
       address  being  looked  up.  Thus,  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.

       Results 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 2.2.

       Each  lookup operation uses the entire address once.  Thus, 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.

       Results are the same as with indexed file lookups.

BUGS

       The table format does not understand quoting conventions.

CONFIGURATION PARAMETERS

       The following main.cf parameters are especially relevant to this topic.
       See the Postfix main.cf file for syntax details and for default values.
       Use the "postfix reload" command after a configuration change.

       virtual_alias_maps
              List of virtual aliasing tables.

       virtual_alias_domains
              List  of virtual alias domains. This uses the same syntax as the
              mydestination parameter.

       propagate_unmatched_extensions
              A list  of  address  rewriting  or  forwarding  mechanisms  that
              propagate  an address extension from the original address to the
              result.  Specify zero or  more  of  canonical,  virtual,  alias,
              forward, include, or generic.

       Other parameters of interest:

       inet_interfaces
              The  network  interface addresses that this system receives mail
              on.  You need to stop and  start  Postfix  when  this  parameter
              changes.

       mydestination
              List of domains that this mail system considers local.

       myorigin
              The  domain that is appended to any address that does not have a
              domain.

       owner_request_special
              Give special treatment to owner-xxx and xxx-request addresses.

       proxy_interfaces
              Other interfaces that this machine receives mail on by way of  a
              proxy agent or network address translator.

SEE ALSO

       cleanup(8), canonicalize and enqueue mail
       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       canonical(5), canonical address mapping

README FILES

       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       DATABASE_README, Postfix lookup table overview
       ADDRESS_REWRITING_README, address rewriting guide
       VIRTUAL_README, domain hosting guide

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

                                                                    VIRTUAL(5)