NAME
virtual - Postfix virtual alias table formatSYNOPSIS
postmap /etc/postfix/virtual postmap -q "string" /etc/postfix/virtual postmap -q - /etc/postfix/virtual <inputfile
DESCRIPTION
The optional 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.
- •
- To redirect mail for one address to one or more addresses.
- •
- 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 recipient address can have its own mailbox.
CASE FOLDING
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.
TABLE FORMAT
The input format for the postmap(1) command is as follows:
- pattern address, address, ...
- When pattern matches a mail address, replace it by the corresponding address.
- 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.
TABLE SEARCH ORDER
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.
- user@domain address, address, ...
- Redirect mail for user@domain to address. This form has the highest precedence.
- user address, address, ...
- Redirect mail for user@site 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 the functionality of the local aliases(5) database. The difference is that mapping can be applied to non-local addresses.
- @domain address, address, ...
- Redirect mail for other users in domain to
address. This form has the lowest precedence.
Note: @ domain is a wild-card. With this form, the Postfix SMTP
server accepts mail for any recipient in domain, 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.
To avoid backscatter with mail for a wild-card domain, replace the wild-card
mapping with explicit 1:1 mappings, or add a reject_unverified_recipient
restriction for that domain:
smtpd_recipient_restrictions = ... reject_unauth_destination check_recipient_access inline:{example.com=reject_unverified_recipient} unverified_recipient_reject_code = 550
In the above example, Postfix may contact a remote server if the recipient is aliased to a remote address.
RESULT ADDRESS REWRITING
The lookup result is subject to address rewriting:
- •
- When the result has the form @otherdomain, the result becomes the same user in otherdomain. This works only for the first address in a multi-address lookup result.
- •
- When "append_at_myorigin=yes", append " @$myorigin" to addresses without "@domain".
- •
- When "append_dot_mydomain=yes", append " .$mydomain" to addresses without ".domain".
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.
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.
/etc/postfix/main.cf: virtual_alias_maps = hash:/etc/postfix/virtual
/etc/postfix/virtual: virtual-alias.domain anything (right-hand content does not matter) [email protected] postmaster [email protected] address1 [email protected] address2, address3
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).
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 available in Postfix 2.5 and later.
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 ($virtual_maps)
- Optional lookup tables that alias specific mail addresses or domains to other local or remote addresses.
- virtual_alias_domains ($virtual_alias_maps)
- Postfix is the final destination for the specified list of virtual alias domains, that is, domains for which all addresses are aliased to addresses in other local or remote domains.
- propagate_unmatched_extensions (canonical, virtual)
- What address lookup tables copy an address extension from the lookup key to the lookup result.
- inet_interfaces (all)
- The network interface addresses that this mail system receives mail on.
- mydestination ($myhostname, localhost.$mydomain, localhost)
- The list of domains that are delivered via the $local_transport mail delivery transport.
- myorigin ($myhostname)
- The domain name that locally-posted mail appears to come from, and that locally posted mail is delivered to.
- owner_request_special (yes)
- Enable special treatment for owner-listname entries in the aliases(5) file, and don't split owner-listname and listname-request address localparts when the recipient_delimiter is set to "-".
- proxy_interfaces (empty)
- The network interface addresses that this mail system receives mail on by way of a proxy or network address translation unit.
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.
ADDRESS_REWRITING_README, address rewriting guide DATABASE_README, Postfix lookup table overview 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 Wietse Venema Google, Inc. 111 8th Avenue New York, NY 10011, USA