SYNOPSIS
postmap /etc/postfix/virtual
postmap -q "string" /etc/postfix/virtual
postmap -q - /etc/postfix/virtual <inputfile
DESCRIPTION
The optional virtual alias table specifies address aliasing for arbi-
trary local or non-local recipient addresses. Virtual aliasing is
recursive, and is done by the Postfix cleanup(8) daemon.
The main applications of virtual aliasing are:
o To redirect mail for one address to one or more addresses.
o 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 recipi-
ent 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 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 corre-
sponding result.
blank lines and comments
user address, address, ...
Mail for user@site is redirected 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 mapping can
be applied to non-local addresses.
@domain address, address, ...
Mail for any user in domain is redirected to address. This form
has the lowest precedence.
In all the above forms, when address has the form @otherdomain, the
result is the same user in otherdomain. This works for the first
address in the expansion only.
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 out-
put from postconf -m for available database types.
/etc/postfix/virtual:
virtual-alias.domain anything (right-hand content does not matter)
Instead of specifying the virtual alias domain name via the vir-
tual_alias_maps table, you may also specify it via the main.cf vir-
tual_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 bro-
ken 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 interpo-
lated 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 in Postfix version 2.1.
Each lookup operation uses the entire address once. Thus, user@domain
mail addresses are not broken up into their user and @domain con-
stituent 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 propa-
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)
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