mailaddr(7) — Linux manual page


MAILADDR(7)                  Linux User's Manual                 MAILADDR(7)

NAME         top

       mailaddr - mail addressing description

DESCRIPTION         top

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


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

            John Doe <>
   (John Doe)

       The domain part ("") 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 ("john.doe") 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:


       (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 ("John Doe") 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 ".":

            "John Q. Doe" <>

       Some mail systems let users abbreviate the domain name.  For
       instance, users at may get away with "john.doe@monet" to
       send mail to John Doe.  This behavior is deprecated.  Sometimes it
       works, but you should not depend on it.

       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:


       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.

       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         top


SEE ALSO         top

       mail(1), aliases(5), forward(5), sendmail(8)

       IETF RFC 5322 ⟨

COLOPHON         top

       This page is part of release 5.08 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

4.2 Berkeley Distribution        2020-08-13                      MAILADDR(7)

Pages that refer to this page: hostname(7)uri(7)url(7)urn(7)