    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, delivery  diagnostics
           are  directed to that address, instead of to the originator of the mes-
           sage.  This is typically used to direct delivery errors  to  the  main-
           tainer  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
                  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 propa-
                  gate an address extension  from  the  original  address  to  the
                  result.  Specify zero or more of canonical, virtual, alias, for-
                  ward, 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)

    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)