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<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
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<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<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, patterns are tried in the order as
       listed below:

       <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 <a href="ADDRESS_CLASS_README.html#virtual_alias_class">virtual alias domains</a>.  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 <a href="virtual.8.html"><b>virtual</b>(8)</a> mail  delivery
       agent.  With  virtual  mailbox domains, 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>