postmap /usr/local/etc/postfix/virtual postmap -q "string" /usr/local/etc/postfix/virtual postmap -q - /usr/local/etc/postfix/virtual <inputfile
The optional virtual(5) alias table rewrites recipient addresses for all local, all virtual, and all remote mail destinations. This is unlike the aliases(5) table which is used only for local(8) delivery. Virtual aliasing is recursive, and is implemented by the Postfix cleanup(8) daemon before mail is queued. The main applications of virtual aliasing are:
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 regexp: or pcre: whose lookup fields can match both upper and lower case.
The input format for the postmap(1) command is as follows:
With lookups from indexed files such as DB or DBM, or from networked tables such as NIS, LDAP or SQL, each user@domain 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.
The lookup result is subject to address rewriting:
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.
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:
/usr/local/etc/postfix/main.cf: virtual_alias_maps = hash:$config_directory/virtualNote: some systems use dbm databases instead of hash. See the output from " postconf -m" for available database types.
/usr/local/etc/postfix/virtual: virtual-alias.domain anything (right-hand content does not matter) firstname.lastname@example.org postmaster email@example.com address1 firstname.lastname@example.org address2, address3The 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@ virtual-alias.domain as undeliverable. Instead of specifying the virtual alias domain name via the virtual_alias_maps table, you may also specify it via the main.cf virtual_alias_domains configuration parameter. This latter parameter uses the same syntax as the main.cf mydestination configuration parameter.
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 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 interpolated as $1, $2 and so on.
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 up to and including Postfix version 2.4. Each lookup operation uses the entire address once. 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. Results are the same as with indexed file lookups.
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.
cleanup(8), canonicalize and enqueue mail postmap(1), Postfix lookup table manager postconf(5), configuration parameters canonical(5), canonical address mapping
Use " postconf readme_directory" or " postconf html_directory" to locate this information.
ADDRESS_REWRITING_README, address rewriting guide DATABASE_README, Postfix lookup table overview VIRTUAL_README, domain hosting guide
The Secure Mailer license must be distributed with this software.
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