mailaddr(7) -- Linux man page
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. For
example, the addresses
Eric Allman <email@example.com>
firstname.lastname@example.org (Eric Allman)
are valid forms of the same address.
The domain part (``monet.berkeley.edu'') may be the name of an internet
host, or it may be a logical mail address. The domain part is not
The local part (``eric'') is often a user name, but its meaning is
defined by the local software. It can be case sensitive, but usually
isn't. 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
inernal 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 first, outside
<>, or last, inside (). (Strictly speaking the two aren't the same,
but the difference is outside the scope of this page.) The name may
have to be quoted using "" if it contains certain characters, most
"Eric P. Allman" <email@example.com>
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.
Under some circumstances it may be necessary to route a message
through several hosts to get it to the final destination. Normally
this happens automatically and invisibly, but sometimes not,
particularly with old and broken software. 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. Some hosts disregard route-addrs and
send directly to hostc.
Route-addrs occur frequently on return addresses, since these are generally
augmented by the software at each host. It is generally possible to ignore
all but the ``user@hostc'' part of the address to determine the actual
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.
FREQUENTLY ASKED QUESTIONS
rtfm.mit.edu and many mirrors store a collection of FAQs. Please find
and use a nearby FAQ archive; there are dozens or hundreds around the
explains how to send mail between many different networks.
lists the top level domains (e.g. ``no'' is Norway and ``ea'' is Eritrea).
gives some useful tips on how to locate e-mail addresses.
RFC822 (Standard for the Format of Arpa Internet Text Messages).