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<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
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<title> Postfix manual - virtual(5) </title>
</head> <body> <pre>
VIRTUAL(5)                                                          VIRTUAL(5)

<b>NAME</b>
       virtual - Postfix virtual alias table format

<b>SYNOPSIS</b>
       <b>postmap /etc/postfix/virtual</b>

       <b>postmap -q "</b><i>string</i><b>" /etc/postfix/virtual</b>

       <b>postmap -q - /etc/postfix/virtual</b> &lt;<i>inputfile</i>

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

       The main applications of virtual aliasing are:

       <b>o</b>      To redirect mail for one address to one or more addresses.

       <b>o</b>      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 <a href="virtual.8.html"><b>virtual</b>(8)</a>
              mail delivery agent. With <a href="ADDRESS_CLASS_README.html#virtual_mailbox_class">virtual mailbox domains</a>, each  recipi-
              ent address can have its own mailbox.

       Virtual  aliasing  is applied only to recipient envelope addresses, and
       does not affect message headers.  Use <a href="canonical.5.html"><b>canonical</b>(5)</a> mapping  to  rewrite
       header and envelope addresses in general.

       Normally,  the  <a href="virtual.5.html"><b>virtual</b>(5)</a> alias table is specified as a text file that
       serves as input to the <a href="postmap.1.html"><b>postmap</b>(1)</a> command.  The result, an indexed file
       in  <b>dbm</b>  or  <b>db</b>  format, is used for fast searching by the mail system.
       Execute  the  command  "<b>postmap  /etc/postfix/virtual</b>"  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 case, the lookups are done in  a
       slightly  different  way  as  described below under "REGULAR EXPRESSION
       TABLES" or "TCP-BASED TABLES".

<b>CASE FOLDING</b>
       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 <a href="regexp_table.5.html">regexp</a>: or <a href="pcre_table.5.html">pcre</a>: whose lookup fields can match both  upper  and
       lower case.

<b>TABLE FORMAT</b>
       The input format for the <a href="postmap.1.html"><b>postmap</b>(1)</a> command is as follows:

       <i>pattern address, address, ...</i>
              When  <i>pattern</i>  matches  a mail address, replace it by the corre-
              sponding <i>address</i>.

       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.

<b>TABLE SEARCH ORDER</b>
       With lookups from indexed files such as DB or DBM,  or  from  networked
       tables  such  as  NIS,  LDAP  or SQL, each <i>user</i>@<i>domain</i> query produces a
       sequence of query patterns as described below.

       Each query pattern is sent to each specified lookup table before trying
       the next query pattern, until a match is found.

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

       <i>user address, address, ...</i>
              Redirect mail for <i>user</i>@<i>site</i> to <i>address</i> when  <i>site</i>  is  equal  to
              $<b><a href="postconf.5.html#myorigin">myorigin</a></b>,  when <i>site</i> is listed in $<b><a href="postconf.5.html#mydestination">mydestination</a></b>, or when it is
              listed in $<b><a href="postconf.5.html#inet_interfaces">inet_interfaces</a></b> or $<b><a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a></b>.

              This functionality overlaps  with  functionality  of  the  local
              <i>aliases</i>(5)  database.  The difference is that <a href="virtual.5.html"><b>virtual</b>(5)</a> mapping
              can be applied to non-local addresses.

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

              Note:  @<i>domain</i>  is a wild-card. With this form, the Postfix SMTP
              server accepts mail for any recipient in <i>domain</i>,  regardless  of
              whether  that  recipient exists.  This may turn your mail system
              into a  backscatter  source:  Postfix  first  accepts  mail  for
              non-existent  recipients  and  then tries to return that mail as
              "undeliverable" to the often forged sender address.

<b>RESULT ADDRESS REWRITING</b>
       The lookup result is subject to address rewriting:

       <b>o</b>      When the result has the form @<i>otherdomain</i>,  the  result  becomes
              the  same  <i>user</i>  in  <i>otherdomain</i>.  This works only for the first
              address in a multi-address lookup result.

       <b>o</b>      When "<b><a href="postconf.5.html#append_at_myorigin">append_at_myorigin</a>=yes</b>", append "<b>@$<a href="postconf.5.html#myorigin">myorigin</a></b>" to  addresses
              without "@domain".

       <b>o</b>      When "<b><a href="postconf.5.html#append_dot_mydomain">append_dot_mydomain</a>=yes</b>", append "<b>.$<a href="postconf.5.html#mydomain">mydomain</a></b>" to addresses
              without ".domain".

<b>ADDRESS EXTENSION</b>
       When a mail address localpart contains the optional recipient delimiter
       (e.g.,  <i>user+foo</i>@<i>domain</i>),  the  lookup  order becomes: <i>user+foo</i>@<i>domain</i>,
       <i>user</i>@<i>domain</i>, <i>user+foo</i>, <i>user</i>, and @<i>domain</i>.

       The  <b><a href="postconf.5.html#propagate_unmatched_extensions">propagate_unmatched_extensions</a></b>  parameter  controls   whether   an
       unmatched address extension (<i>+foo</i>) is propagated to the result of table
       lookup.

<b>VIRTUAL ALIAS DOMAINS</b>
       Besides virtual aliases, the virtual alias table can also  be  used  to
       implement  virtual  alias  domains.  With  a  <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domain</a>, 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 <a href="virtual.8.html"><b>virtual</b>(8)</a> mail delivery
       agent. With <a href="ADDRESS_CLASS_README.html#virtual_mailbox_class">virtual mailbox domains</a>, each recipient  address  can  have
       its own mailbox.

       With  a  <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domain</a>, 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 <a href="aliases.5.html"><b>aliases</b>(5)</a> and local mailing lists
       are not visible as <i>localname@virtual-alias.domain</i>.

       Support for a <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domain</a> looks like:

       /etc/postfix/<a href="postconf.5.html">main.cf</a>:
           <a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a> = <a href="DATABASE_README.html#types">hash</a>:/etc/postfix/virtual

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

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

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

       Do  not specify <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domain</a> names in the <a href="postconf.5.html"><b>main.cf</a> <a href="postconf.5.html#mydestination">mydestination</a></b>
       or <b><a href="postconf.5.html#relay_domains">relay_domains</a></b> configuration parameters.

       With a <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domain</a>, the Postfix SMTP server accepts  mail  for
       <i>known-user@virtual-alias.domain</i>, and rejects mail for <i>unknown-user</i>@<i>vir-</i>
       <i>tual-alias.domain</i> as undeliverable.

       Instead of specifying the  virtual  alias  domain  name  via  the  <b><a href="postconf.5.html#virtual_alias_maps">vir</a>-</b>
       <b><a href="postconf.5.html#virtual_alias_maps">tual_alias_maps</a></b>  table,  you  may  also specify it via the <a href="postconf.5.html"><b>main.cf</a> <a href="postconf.5.html#virtual_alias_domains">vir-</b>
       <b>tual_alias_domains</a></b> configuration parameter.  This latter parameter uses
       the same syntax as the <a href="postconf.5.html"><b>main.cf</a> <a href="postconf.5.html#mydestination">mydestination</a></b> configuration parameter.

<b>REGULAR EXPRESSION TABLES</b>
       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 <a href="regexp_table.5.html"><b>regexp_table</b>(5)</a> or <a href="pcre_table.5.html"><b>pcre_table</b>(5)</a>.

       Each  pattern  is  a  regular  expression that is applied to the entire
       address being looked up. Thus, <i>user@domain</i> mail addresses are not  bro-
       ken  up  into their <i>user</i> and <i>@domain</i> constituent parts, nor is <i>user+foo</i>
       broken up into <i>user</i> and <i>foo</i>.

       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  interpo-
       lated as <b>$1</b>, <b>$2</b> and so on.

<b>TCP-BASED TABLES</b>
       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 <a href="tcp_table.5.html"><b>tcp_table</b>(5)</a>.  This feature is not
       available up to and including Postfix version 2.4.

       Each lookup operation uses the entire address once.  Thus,  <i>user@domain</i>
       mail  addresses  are  not  broken  up  into their <i>user</i> and <i>@domain</i> con-
       stituent parts, nor is <i>user+foo</i> broken up into <i>user</i> and <i>foo</i>.

       Results are the same as with indexed file lookups.

<b>BUGS</b>
       The table format does not understand quoting conventions.

<b>CONFIGURATION PARAMETERS</b>
       The following <a href="postconf.5.html"><b>main.cf</b></a> parameters are especially relevant to this topic.
       See the Postfix <a href="postconf.5.html"><b>main.cf</b></a> file for syntax details and for default values.
       Use the "<b>postfix reload</b>" command after a configuration change.

       <b><a href="postconf.5.html#virtual_alias_maps">virtual_alias_maps</a></b>
              List of virtual aliasing tables.

       <b><a href="postconf.5.html#virtual_alias_domains">virtual_alias_domains</a></b>
              List of <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domains</a>. This uses the same syntax as  the
              <b><a href="postconf.5.html#mydestination">mydestination</a></b> parameter.

       <b><a href="postconf.5.html#propagate_unmatched_extensions">propagate_unmatched_extensions</a></b>
              A list of address rewriting or forwarding mechanisms that propa-
              gate an address extension  from  the  original  address  to  the
              result.  Specify zero or more of <b>canonical</b>, <b>virtual</b>, <b>alias</b>, <b>for-</b>
              <b>ward</b>, <b>include</b>, or <b>generic</b>.

       Other parameters of interest:

       <b><a href="postconf.5.html#inet_interfaces">inet_interfaces</a></b>
              The network interface addresses that this system  receives  mail
              on.   You  need  to  stop  and start Postfix when this parameter
              changes.

       <b><a href="postconf.5.html#mydestination">mydestination</a></b>
              List of domains that this mail system considers local.

       <b><a href="postconf.5.html#myorigin">myorigin</a></b>
              The domain that is appended to any address that does not have  a
              domain.

       <b><a href="postconf.5.html#owner_request_special">owner_request_special</a></b>
              Give special treatment to <b>owner-</b><i>xxx</i> and <i>xxx</i><b>-request</b> addresses.

       <b><a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a></b>
              Other  interfaces that this machine receives mail on by way of a
              proxy agent or network address translator.

<b>SEE ALSO</b>
       <a href="cleanup.8.html">cleanup(8)</a>, canonicalize and enqueue mail
       <a href="postmap.1.html">postmap(1)</a>, Postfix lookup table manager
       <a href="postconf.5.html">postconf(5)</a>, configuration parameters
       <a href="canonical.5.html">canonical(5)</a>, canonical address mapping

<b>README FILES</b>
       <a href="ADDRESS_REWRITING_README.html">ADDRESS_REWRITING_README</a>, address rewriting guide
       <a href="DATABASE_README.html">DATABASE_README</a>, Postfix lookup table overview
       <a href="VIRTUAL_README.html">VIRTUAL_README</a>, domain hosting guide

<b>LICENSE</b>
       The Secure Mailer license must be distributed with this software.

<b>AUTHOR(S)</b>
       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

                                                                    VIRTUAL(5)
</pre> </body> </html>