VIRTUAL(5) VIRTUAL(5)
NAME
virtual - format of Postfix virtual table
SYNOPSIS
postmap /etc/postfix/virtual
DESCRIPTION
The optional virtual table specifies address redirections
for local and non-local recipients or domains. The redi-
rections are used by the cleanup(8) daemon. The redirec-
tions are recursive.
The virtual redirection is applied only to recipient enve-
lope 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 gen-
eral.
Normally, the virtual 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 expres-
sions. In that case, the lookups are done in a slightly
different way as described below.
POSTFIX-STYLE VIRTUAL DOMAINS
With a Postfix-style virtual domain, the virtual domain
has its own user name space. Local (i.e. non-virtual)
usernames are not visible in a Postfix-style virtual
domain. In particular, local aliases(5) and mailing lists
are not visible as localname@virtual.domain.
Use a Sendmail-style virtual domain (see below) if local
usernames, aliases(5) or mailing lists should be visible
as localname@virtual.domain.
Support for a Postfix-style virtual domain looks like:
/etc/postfix/virtual:
virtual.domain anything (right-hand content does not matter)
postmaster@virtual.domain postmaster
user1@virtual.domain address1
user2@virtual.domain address2, address3
The virtual.domain anything entry is required for a
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VIRTUAL(5) VIRTUAL(5)
Postfix-style virtual domain.
Do not list a Postfix-style virtual domain in the main.cf
mydestination configuration parameter. Such an entry is
required only for a Sendmail-style virtual domain.
With a Postfix-style virtual domain, the Postfix SMTP
server accepts mail for known-user@virtual.domain and
rejects mail for unknown-user@virtual.domain as undeliver-
able.
SENDMAIL-STYLE VIRTUAL DOMAINS
With a Sendmail-style virtual domain, every local (i.e.
non-virtual) username is visible in the virtual domain. In
particular, every local alias and mailing list is visible
as localname@virtual.domain.
Use a Postfix-style virtual domain (see above) if local
usernames, aliases(5) or mailing lists should not be visi-
ble as localname@virtual.domain.
Support for a Sendmail-style virtual domain looks like:
/etc/postfix/main.cf:
mydestination = $myhostname localhost.$mydomain $mydomain
virtual.domain
/etc/postfix/virtual:
user1@virtual.domain address1
user2@virtual.domain address2, address3
The main.cf mydestination entry is required for a Send-
mail-style virtual domain.
Do not specify a virtual.domain whatever virtual map entry
for a Sendmail-style virtual domain. Such an entry is
required only with a Postfix-style virtual domain.
With a Sendmail-style virtual domain, the Postfix local
delivery agent delivers mail for an unknown user@vir-
tual.domain to a local (i.e. non-virtual) user that has
the same name; if no such recipient exists, the Postfix
local delivery agent bounces the mail to the sender.
TABLE FORMAT
The format of the virtual table is as follows, mappings
being tried in the order as listed in this manual page:
blanks and comments
Blank lines are ignored, as are lines beginning
with `#'.
leading whitespace
Lines that begin with whitespace continue the
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VIRTUAL(5) VIRTUAL(5)
previous line.
pattern result
When pattern matches a mail address, replace it by
the corresponding result.
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, ...
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 alias(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 @other-
domain, the result is the same user in otherdomain. This
works for the first address in the expansion only.
ADDRESS EXTENSION
When the search fails, and the address localpart contains
the optional recipient delimiter (e.g., user+foo@domain),
the search is repeated for the unextended address (e.g.
user@domain), and the unmatched address extension is prop-
agated to the result of expansion. The matching order is:
user+foo@domain, user@domain, user+foo, user, and @domain.
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
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VIRTUAL(5) VIRTUAL(5)
table, until a pattern is found that matches the search
string.
Results are the same as with normal indexed file lookups,
with the additional feature that parenthesized substrings
from the pattern can be interpolated as $1, $2 and so on.
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_maps
List of virtual mapping tables.
Other parameters of interest:
inet_interfaces
The network interface addresses that this system
receives mail on.
mydestination
List of domains that this mail system considers
local.
myorigin
The domain that is appended to locally-posted mail.
owner_request_special
Give special treatment to owner-xxx and xxx-request
addresses.
SEE ALSO
cleanup(8) canonicalize and enqueue mail
postmap(1) create mapping table
pcre_table(5) format of PCRE tables
regexp_table(5) format of POSIX regular expression tables
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
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