Ubuntu Manpage: aliases - Postfix local alias database format

Provided by: postfix_3.3.0-1ubuntu0.4_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, 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. 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 (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)
              The alias databases that are used for local(8) delivery.

       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 a user name from its extension (example: user+foo),  or  a
              .forward file name from its extension (example: .forward+foo).

       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)