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

       mailaddr - mail addressing description

       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.


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

       IETF RFC 5322 <>

       This  page  is  part of release 5.05 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         2017-05-03                       MAILADDR(7)
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