aliases(4)

Synopsis

   /etc/mail/aliases
   ~/.forward

Description

/etc/passwd

Mail addresses (usernames) of local users.

/etc/mail/aliases

Aliases for the local host, in ASCII format. This file can be edited to add, update, or delete local mail aliases.

/etc/mail/aliases.db

The aliasing information from /etc/mail/aliases, in binary, dbm format for use by sendmail. newaliases(1M) maintains these files.

Addresses

• Local usernames:

  
  username

  Each local username is listed in the local host's /etc/passwd file.

• Local filenames:

  
  pathname

  Messages addressed to the absolute pathname of a file are appended to that file.

• Commands:

  
  |command

  If the first character of the address is a vertical bar (|), sendmail pipes the message to the standard input of the command the bar precedes.

• Include files:

  
  pathname

  The aliases in pathname are added to the aliases for name.

• E-mail addresses (RFC 822 format):

  
  username@domain

  If domain does not contain any dots, then it is interpreted as the name of a host in the current domain. Otherwise, the message is passed to a ``mailhost'' that determines how to get to the specified domain. Domains are divided into subdomains separated by dots, with the top-level domain on the right. Top-level domains include:

  • commercial organizations

  • educational organizations

  • government organizations

  • military organizations

  For example, the full address of John Smith could be:

  js@jsmachine.Podunk-U.EDU
  

  if he uses the machine named jsmachine at Podunk University.

• UUCP addresses:
  
  . . . [host!] host!username

  These are sometimes mistakenly referred to as ``Usenet'' addresses. UUCP provides links to numerous sites throughout the world for the remote copying of files.

  Other site-specific forms of addressing can be added by customizing the sendmail configuration file. See the sendmail(1M) manual page for details. Standard addresses are recommended.

Aliases

• Local aliases:

  /etc/mail/aliases is formatted as a series of lines of the form:
  
  aliasname:address[, address]

  aliasname is the name of the alias or alias group, and address is the address of a recipient in the group. Aliases can be nested. That is, an address can be the name of another alias group. Because of the way sendmail performs mapping from upper-case to lower-case, an address that is the name of another alias group must not contain any upper-case letters.

  Lines beginning with white space are treated as continuation lines for the preceding alias. Lines beginning with a hash sign (#) are comments.

• Special aliases:

  An alias of the form:
  
  owner- aliasname : address

  directs error-messages resulting from mail to aliasname to address, instead of back to the person who sent the message.

  An alias of the form:
  
  aliasname:
  :include:pathname

  with colons as shown, adds the recipients listed in the file pathname to the aliasname alias. This allows a private list to be maintained separately from the aliases file.

• NIS domain aliases:

  Normally, the aliases maps on the master NIS server are used for the mail.aliases NIS map, which can be made available to every NIS client. With NIS, the local /etc/mail/aliases file is consulted first, then the maps on the NIS server. Thus, the /etc/mail/aliases* files on the various hosts in a network will one day be obsolete. Domain-wide aliases should ultimately be resolved into usernames on specific hosts. For example, if the following were in the domain-wide alias file:

  jsmith:js@jsmachine
  

  then any NIS client could just mail to jsmith and not have to remember the machine and username for John Smith. If a NIS alias does not resolve to an address with a specific host, then the name of the NIS domain is used. There should be an alias of the domain name for a host in this case. For example, the alias:

     jsmith:root
  

  sends mail on a NIS client to root@podunk-u if the name of the NIS domain is podunk-u.

Files

/etc/passwd

/etc/mail/aliases

/var/yp/domainname/mail.aliases

Corresponding NIS map containing aliases and mail addresses. The alias is the key in the map.

/var/yp/domainname/mail.byaddr

Same as mail.aliases, except key is mail address instead of alias.

References