2. EL 8
  3. postfix
  4. aliases(5)

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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 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:



  

  
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.



  

  
The alias databases for local(8) delivery that are updated with
      "newaliases" or with "sendmail
    -bi".

  

  
The alias databases that are used for local(8) delivery.

  

  
Restrict local(8) mail delivery to external commands.

  

  
Restrict local(8) mail delivery to external files.

  

  
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.

  

  
What address lookup tables copy an address extension from the lookup key
      to the lookup result.

  

  
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 "-".

  

  
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:



  

  
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