mailaddr(7)

NAME

   mailaddr - mail addressing description

DESCRIPTION

   This  manual page gives a brief introduction to SMTP mail addresses, as
   used on the Internet.  These addresses are in the general format

        user@domain

   where a domain is a  hierarchical  dot-separated  list  of  subdomains.
   These examples are valid forms of the same address:

        eric@monet.berkeley.edu
        Eric Allman <eric@monet.berkeley.edu>
           eric@monet.berkeley.edu (Eric Allman)

   The  domain part ("monet.berkeley.edu") is a mail-accepting domain.  It
   can be a host and in the past it usually was, but it  doesn't  have  to
   be.  The domain part is not case sensitive.

   The local part ("eric") is often a username, but its meaning is defined
   by the local software.  Sometimes it is case sensitive,  although  that
   is  unusual.   If  you  see a local-part that looks like garbage, it is
   usually because of a gateway between an internal e-mail system and  the
   net, here are some examples:

        "surname/admd=telemail/c=us/o=hp/prmd=hp"@some.where
        USER%SOMETHING@some.where
        machine!machine!name@some.where
        I2461572@some.where

   (These  are,  respectively, an X.400 gateway, a gateway to an arbitrary
   internal mail system  that  lacks  proper  internet  support,  an  UUCP
   gateway, and the last one is just boring username policy.)

   The  real-name  part ("Eric Allman") can either be placed before <>, or
   in () at the end.  (Strictly speaking the two aren't the same, but  the
   difference  is beyond the scope of this page.)  The name may have to be
   quoted using "", for example, if it contains ".":

        "Eric P. Allman" <eric@monet.berkeley.edu>

   Abbreviation.
   Many mail systems let users abbreviate the domain name.  For  instance,
   users  at  berkeley.edu  may get away with "eric@monet" to send mail to
   Eric Allman.  This behavior is deprecated.  Sometimes it works, but you
   should not depend on it.

   Route-addrs.
   In the past, sometimes one had to route a message through several hosts
   to get it to its final destination.  Addresses which show these  relays
   are termed "route-addrs".  These use the syntax:

        <@hosta,@hostb:user@hostc>

   This  specifies that the message should be sent to hosta, from there to
   hostb, and finally to hostc.  Many hosts disregard route-addrs and send
   directly to hostc.

   Route-addrs  are  very  unusual  now.  They occur sometimes in old mail
   archives.  It is generally possible to ignore all but the  "user@hostc"
   part of the address to determine the actual address.

   Postmaster.
   Every  site  is  required  to  have  a  user  or  user alias designated
   "postmaster" to which problems with the mail system may  be  addressed.
   The "postmaster" address is not case sensitive.

FILES

   /etc/aliases
   ~/.forward

SEE ALSO

   binmail(1),  mail(1), mconnect(1), aliases(5), forward(5), sendmail(8),
   vrfy(8)

   RFC 2822 (Internet Message Format)

COLOPHON

   This page is part of release 4.09 of the Linux  man-pages  project.   A
   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.

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