aliases(5) — Linux manual page


ALIASES(5)               BSD File Formats Manual              ALIASES(5)

NAME         top

     aliases — aliases file for smtpd

DESCRIPTION         top

     This manual page describes the format of the aliases file, as used
     by smtpd(8).  An alias, in its simplest form, is used to assign an
     arbitrary name to an email address or a group of email addresses.
     This provides a convenient way to send mail.  For example an alias
     could refer to all users of a group: email to that alias would be
     sent to all members of the group.  Much more complex aliases can be
     defined however: an alias can refer to other aliases, be used to
     send mail to a file instead of another person, or to execute
     various commands.

     Within the file, ‘#’ is a comment delimiter; anything placed after
     it is discarded.  The file consists of key/value mappings of the

           key: value1, value2, value3, ...

     key is always folded to lowercase before alias lookups to ensure
     that there can be no ambiguity.  The key is expanded to the
     corresponding values, which consist of one or more of the

     user    A user on the host machine.  The user must have a valid
             entry in the passwd(5) database file.

             Append messages to file, specified by its absolute

             Pipe the message to command on its standard input.  The
             command is run under the privileges of the daemon's
             unprivileged account.

             Include any definitions in file as alias entries.  The
             format of the file is identical to this one.

             An email address in RFC 5322 format.  If an address
             extension is appended to the user-part, it is first
             compared for an exact match.  It is then stripped so that
             an address such as will only use the
             part that precedes ‘+’ as a key.

     error:code message
             A status code and message to return.  The code must be 3
             digits, starting 4XX (TempFail) or 5XX (PermFail).  The
             message must be present and can be freely chosen.

FILES         top

     /etc/mail/aliases     Default aliases file.

SEE ALSO         top

     smtpd.conf(5), makemap(8), newaliases(8), smtpd(8)

HISTORY         top

     The aliases file format appeared in 4.0BSD.

COLOPHON         top

     This page is part of the OpenSMTPD (a FREE implementation of the
     server-side SMTP protocol) project.  Information about the project
     can be found at  If you have a bug
     report for this manual page, see
     ⟨⟩.  This page was
     obtained from the project's upstream Git repository
     ⟨⟩ on 2023-06-23.  (At
     that time, the date of the most recent commit that was found in the
     repository was 2023-06-23.)  If you discover any rendering problems
     in this HTML version of the page, or you believe there is a better
     or more up-to-date source for the page, or you have corrections or
     improvements to the information in this COLOPHON (which is not part
     of the original manual page), send a mail to

BSD                         February 13, 2021                        BSD

Pages that refer to this page: setaliasent(3)mailaddr(7)