Ubuntu Manpage: aliases - Postfix local alias database format

NAME

       aliases - Postfix local alias database format

SYNOPSIS

       newaliases

DESCRIPTION

The optional aliases(5) table (alias_maps) redirects mail for local recipients. The
redirections are processed by the Postfix local(8) delivery agent.

This is unlike virtual(5) aliasing (virtual_alias_maps) which applies to all recipients:
local(8), virtual, and remote, and which is implemented by the cleanup(8) daemon.

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, this will override the envelope sender
address, so that delivery diagnostics are directed to owner-name, instead of the
originator of the message (for details, see owner_request_special, expand_owner_alias and
reset_owner_alias). 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. For details on how a file is written see the
sections "EXTERNAL FILE DELIVERY" and "DELIVERY RIGHTS" in the local(8)
documentation. 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. For details on how a command
is executed see "EXTERNAL COMMAND DELIVERY" and "DELIVERY RIGHTS" in the local(8)
documentation.

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 (see 'postconf -d' output)
              The alias databases for local(8) delivery that are  updated  with  "newaliases"  or
              with "sendmail -bi".

       alias_maps (see 'postconf -d' output)
              Optional lookup tables with aliases that apply only to local(8) recipients; this is
              unlike virtual_alias_maps that apply to  all  recipients:  local(8),  virtual,  and
              remote.

       allow_mail_to_commands (alias, forward)
              Restrict local(8) mail delivery to external commands.

       allow_mail_to_files (alias, forward)
              Restrict local(8) mail delivery to external files.

       expand_owner_alias (no)
              When  delivering  to  an  alias "aliasname" that has an "owner-aliasname" companion
              alias, set the envelope sender address to the expansion  of  the  "owner-aliasname"
              alias.

       propagate_unmatched_extensions (canonical, virtual)
              What  address  lookup  tables  copy an address extension from the lookup key to the
              lookup result.

       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 "-".

       recipient_delimiter (empty)
              The set of characters that can separate an email address localpart, user name, or a
              .forward file name from its extension.

       Available in Postfix version 2.3 and later:

       frozen_delivered_to (yes)
              Update  the  local(8)  delivery  agent's  idea  of  the  Delivered-To: address (see
              prepend_delivered_header) only once, at the start of a  delivery  attempt;  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)