VIRTUAL(5) File Formats Manual VIRTUAL(5)
virtual - format of Postfix virtual alias table
postmap -q "string" /etc/postfix/virtual
postmap -q - /etc/postfix/virtual <<inputfile
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
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. In that case, the
lookups are done in a slightly different way as described below.
The input format for the postmap(1) command is as follows:
When pattern matches a mail address, replace it by the corre-
blank lines and comments
Empty lines and whitespace-only lines are ignored, as are lines
whose first non-whitespace character is a `#'.
A logical line starts with non-whitespace text. A line that
starts with whitespace continues a logical line.
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
user@domain address, address, ...
Mail for user@domain is redirected to address. This form has
the highest precedence.
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.
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.
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. An unmatched address exten-
sion (+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 email@example.com.
Support for a virtual alias domain looks like:
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.
virtual-alias.domain anything (right-hand content does not matter)
firstname.lastname@example.org 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
email@example.com, and rejects mail for unknown-user@vir-
tual-alias.domain as undeliverable.
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.
The table format does not understand quoting conventions.
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.
List of virtual aliasing tables.
List of virtual alias domains. This uses the same syntax as the
Other parameters of interest:
The network interface addresses that this system receives mail
on. You need to stop and start Postfix when this parameter
List of domains that this mail system considers local.
The domain that is appended to any address that does not have a
Give special treatment to owner-xxx and xxx-request addresses.
cleanup(8) canonicalize and enqueue mail
postmap(1) create mapping table
regexp_table(5) POSIX regular expression table format
pcre_table(5) Perl Compatible Regular Expression table format
The Secure Mailer license must be distributed with this software.
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA