Ubuntu Manpage: aliases - Postfix local alias database format

Provided by: postfix_3.1.0-3ubuntu0.4_amd64

NAME

       aliases - Postfix local alias database format

SYNOPSIS

       newaliases

DESCRIPTION

The aliases(5) table provides a system-wide mechanism to redirect mail for local
recipients. The redirections are processed by the Postfix local(8) delivery agent.

Normally, the aliases(5) table is specified as a text file that serves as input to the
postalias(1) command. The result, an indexed file in dbm or db format, is used for fast
lookup by the mail system. Execute the command newaliases in order to rebuild the indexed
file after changing the Postfix alias database.

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 this case, the lookups are done in a slightly different
way as described below under "REGULAR EXPRESSION TABLES".

Users can control delivery of their own mail by setting up .forward files in their home
directory. Lines in per-user .forward files have the same syntax as the right-hand side
of aliases(5) entries.

The format of the alias database input file is as follows:

• An alias definition has the form

name: value1, value2, ...

• 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.

The name is a local address (no domain part). Use double quotes when the name contains
any special characters such as whitespace, `#', `:', or `@'. The name is folded to
lowercase, in order to make database lookups case insensitive.

In addition, when an alias exists for owner-name, delivery diagnostics are directed to
that address, instead of to the originator of the message. This is typically used to
direct delivery errors to the maintainer of a mailing list, who is in a better position to
deal with mailing list delivery problems than the originator of the undelivered mail.

The value contains one or more of the following:

address
Mail is forwarded to address, which is compatible with the RFC 822 standard.

/file/name
Mail is appended to /file/name. See local(8) for details of delivery to file.
Delivery is not limited to regular files. For example, to dispose of unwanted
mail, deflect it to /dev/null.

|command
Mail is piped into command. Commands that contain special characters, such as
whitespace, should be enclosed between double quotes. See local(8) for details of
delivery to command.

When the command fails, a limited amount of command output is mailed back to the
sender. The file /usr/include/sysexits.h defines the expected exit status codes.
For example, use "|exit 67" to simulate a "user unknown" error, and "|exit 0" to
implement an expensive black hole.

:include:/file/name
Mail is sent to the destinations listed in the named file. Lines in :include:
files have the same syntax as the right-hand side of alias entries.

A destination can be any destination that is described in this manual page.
However, delivery to "|command" and /file/name is disallowed by default. To enable,
edit the allow_mail_to_commands and allow_mail_to_files configuration parameters.

ADDRESS EXTENSION

       When  alias  database  search  fails,  and  the  recipient localpart contains the optional
       recipient delimiter (e.g., user+foo), the search is repeated for  the  unextended  address
       (e.g., user).

       The   propagate_unmatched_extensions  parameter  controls  whether  an  unmatched  address
       extension (+foo) is propagated to the result of table lookup.

CASE FOLDING

       The local(8) delivery agent always folds the search string to  lowercase  before  database
       lookup.

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).  NOTE:  these  formats  do not use ":" at the end of a
       pattern.

       Each regular expression is applied to the entire search  string.  Thus,  a  search  string
       user+foo is not broken up into user and foo.

       Regular  expressions  are  applied in the order as specified in the table, until a regular
       expression is found that matches the search string.

       Lookup results are the same as with indexed file lookups.  For security reasons  there  is
       no support for $1, $2 etc. substring interpolation.

SECURITY

       The  local(8)  delivery  agent  disallows  regular  expression  substitution of $1 etc. in
       alias_maps, because that would open a security hole.

       The local(8) delivery agent will silently ignore requests to use  the  proxymap(8)  server
       within  alias_maps.  Instead it will open the table directly.  Before Postfix version 2.2,
       the local(8) delivery agent will terminate with a fatal error.

CONFIGURATION PARAMETERS

The following main.cf parameters are especially relevant. The text below provides only a
parameter summary. See postconf(5) for more details including examples.

alias_database
List of alias databases that are updated by the newaliases(1) command.

alias_maps
List of alias databases queried by the local(8) delivery agent.

allow_mail_to_commands
Restrict the usage of mail delivery to external command.

allow_mail_to_files
Restrict the usage of mail delivery to external file.

expand_owner_alias
When delivering to an alias that has an owner- companion alias, set the envelope
sender address to the right-hand side of the owner alias, instead using of the
left-hand side address.

propagate_unmatched_extensions
A list of address rewriting or forwarding mechanisms that propagate an address
extension from the original address to the result. Specify zero or more of
canonical, virtual, alias, forward, include, or generic.

owner_request_special
Give special treatment to owner-listname and listname-request addresses.

recipient_delimiter
Delimiter that separates recipients from address extensions.

Available in Postfix version 2.3 and later:

frozen_delivered_to
Update the local(8) delivery agent's Delivered-To: address (see
prepend_delivered_header) only once, at the start of a delivery; do not update the
Delivered-To: address while expanding aliases or .forward files.

STANDARDS

       RFC 822 (ARPA Internet Text Messages)

README FILES

       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       DATABASE_README, Postfix lookup table overview

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

                                                                                       ALIASES(5)