Aliases

   Aliases have multiple uses with e-mail. Individual users
   typically use aliases as abbreviations. For instance, rather
   than remember John Doe's full e-mail address, an alias JD can
   be created so that mail sent to the address JD is properly sent
   using John Doe's full address (e.g., JD573@VAXC.EXAMPLE.COM).
   System managers often use aliases in order to create valid mail
   addresses for non-existent users. For instance, an alias named
   Postmaster might be created and equated with the username SYSTEM
   so that incoming network mail for the user Postmaster is routed
   to the SYSTEM account. These are just two examples of the many
   practical uses of aliases.

   The process of interpreting an alias is called "alias expansion".
   In the two examples above, the aliases JD and Postmaster expand,
   respectively, to JD573@VAXC.EXAMPLE.COM and SYSTEM.

   In this documentation, the expansion of an alias is represented
   with the following notation
            alias-name - >  alias-value

   For example, John - >  JD573@VAXC.EXAMPLE.COM.

   PMDF alias names are "case insensitive". This means that the
   alias names jd, JD, jD, and Jd are all considered to be identical
   by PMDF; the case (upper versus lower case) of the individual
   characters in an alias name is irrelevant to PMDF. However, PMDF
   does preserve the case of alias values.

   PMDF aliases can expand to:

   -  an address: JD - >  JD573@VAXC.EXAMPLE.COM,

   -  a list of addresses: STAFF - >
      BOB@EXAMPLE.COM,SUE@EXAMPLE.COM,

   -  other aliases: JD - >  JOHND - > JD573@VAXC.EXAMPLE.COM,

   -  a list of aliases: COMPANY - >  STAFF,ADMIN,FACULTY, or

   -  a mixture of addresses and aliases: LIST - >
      STAFF,BOB@EXAMPLE.COM.

   Note that in the above example, it is not clear whether or not
   the expanded value of an alias is another alias or not; i.e.,
   in "JD - >  JOHND", JOHND could have been either an alias or
   a legitimate username. PMDF always starts by assuming that an
   address without any domain part (e.g., @EXAMPLE.COM) is an alias
   and attempts to expand it. When expanding an alias, PMDF first
   tries to look up the alias in the user's personal alias database
   and, if the alias is not found there, then PMDF consults system-
   level alias sources. After expanding an alias once, PMDF then
   tries to expand the result (or results in the case of a list).
   This expansion process is repeated until no more expansions are
   possible at which point the results are all assumed to be real
   mail addresses and not aliases.

   By default, alias names can be from 1 to 80 characters long and
   their expansion values 0 to 252 characters. This corresponds
   to a "long" alias database file which is the type of file DB
   normally creates. When a "huge" alias database file is used, the
   maximum lengths of the alias names and their expansion values
   are, respectively, 80 and 1024 characters. When a "short" alias
   database file is used, the maximum lengths of the alias names and
   their expansion values are, respectively, 32 and 80 characters.
   Note that by default the system alias database created with the
   CRDB utility is a short alias database.

   When specifying mail addresses within VMS MAIL or DECwindows
   MAIL, PMDF aliases must be specified using the format IN%alias-
   name. For example, mail addressed as follows

   MAIL> SEND
   To:   IN%JD

   would use PMDF's alias for JD, if any exists. From PMDF MAIL, you
   can simply use JD rather than IN%JD.

   System managers can find it useful to establish forwarding for
   commonly used system wide aliases. For example,

   MAIL> SET FORWARD/USER=POSTMASTER IN%Postmaster

   with Postmaster a PMDF alias (in the system alias database) which
   points to the user or users who should receive mail intended for
   the system's postmaster. When this type of forwarding has been
   set up, users can then just send mail to the (fictitious) user
   POSTMASTER,

   MAIL> SEND
   To:   POSTMASTER

   and PMDF will route it to the proper individuals.