man > ALIASES

ALIASES(5)                               File Formats Manual                              ALIASES(5)

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 de‐
       scribed below under "REGULAR EXPRESSION TABLES".

       Users can control delivery of their own mail by setting up .forward files in their  home  di‐
       rectory.   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-white‐
              space 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 ad‐
       dress, 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  re‐
       set_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.  Deliv‐
              ery is not limited to regular files.  For example, to dispose of  unwanted  mail,  de‐
              flect it to /dev/null.

       |command
              Mail  is  piped into command. Commands that contain special characters, such as white‐
              space, should be enclosed between double quotes. For details on how a command is  exe‐
              cuted see "EXTERNAL COMMAND DELIVERY" and "DELIVERY RIGHTS" in the local(8) documenta‐
              tion.

              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 reg‐
       exp_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 ex‐
       pression 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 pa‐
       rameter 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_delim‐
              iter 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)

SEE ALSO
       local(8), local delivery agent
       newaliases(1), create/update alias database
       postalias(1), create/update alias database
       postconf(5), configuration parameters

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)