# Postfix manual - aliases(5)

    ALIASES(5)                                                          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 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:

           o      An alias definition has the form

                       name: value1, value2, ...

           o      Empty  lines and whitespace-only lines are ignored, as are lines
                  whose first non-whitespace character is a `#'.

           o      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  char-
                  acters,  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 imple-
                  ment 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_com-
                  mands 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  list-
                  name-request address localparts when the recipient_delimiter  is
                  set to "-".

           recipient_delimiter (empty)
                  The  set of characters that can separate an email address local-
                  part, 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
           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)