1mailaddr(7)            Miscellaneous Information Manual            mailaddr(7)
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NAME

6       mailaddr - mail addressing description
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DESCRIPTION

9       This  manual page gives a brief introduction to SMTP mail addresses, as
10       used on the Internet.  These addresses are in the general format
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12           user@domain
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14       where a domain is a  hierarchical  dot-separated  list  of  subdomains.
15       These examples are valid forms of the same address:
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17           john.doe@monet.example.com
18           John Doe <john.doe@monet.example.com>
19           john.doe@monet.example.com (John Doe)
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21       The  domain  part ("monet.example.com") is a mail-accepting domain.  It
22       can be a host and in the past it usually was, but it  doesn't  have  to
23       be.  The domain part is not case sensitive.
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25       The local part ("john.doe") is often a username, but its meaning is de‐
26       fined by the local software.  Sometimes it is case sensitive,  although
27       that  is  unusual.  If you see a local-part that looks like garbage, it
28       is usually because of a gateway between an internal e-mail  system  and
29       the net, here are some examples:
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31           "surname/admd=telemail/c=us/o=hp/prmd=hp"@some.where
32           USER%SOMETHING@some.where
33           machine!machine!name@some.where
34           I2461572@some.where
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36       (These  are,  respectively, an X.400 gateway, a gateway to an arbitrary
37       internal mail system that lacks proper internet support, an UUCP  gate‐
38       way, and the last one is just boring username policy.)
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40       The  real-name  part ("John Doe") can either be placed before <>, or in
41       () at the end.  (Strictly speaking the two aren't  the  same,  but  the
42       difference  is beyond the scope of this page.)  The name may have to be
43       quoted using "", for example, if it contains ".":
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45           "John Q. Doe" <john.doe@monet.example.com>
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47   Abbreviation
48       Some mail systems let users abbreviate the domain name.  For  instance,
49       users at example.com may get away with "john.doe@monet" to send mail to
50       John Doe.  This behavior is deprecated.  Sometimes it  works,  but  you
51       should not depend on it.
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53   Route-addrs
54       In the past, sometimes one had to route a message through several hosts
55       to get it to its final destination.  Addresses which show these  relays
56       are termed "route-addrs".  These use the syntax:
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58           <@hosta,@hostb:user@hostc>
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60       This  specifies that the message should be sent to hosta, from there to
61       hostb, and finally to hostc.  Many hosts disregard route-addrs and send
62       directly to hostc.
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64       Route-addrs are very unusual now.  They occur sometimes in old mail ar‐
65       chives.  It is generally possible to ignore all  but  the  "user@hostc"
66       part of the address to determine the actual address.
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68   Postmaster
69       Every  site  is required to have a user or user alias designated "post‐
70       master" to which problems with the mail system may be  addressed.   The
71       "postmaster" address is not case sensitive.
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FILES

74       /etc/aliases
75       ~/.forward
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SEE ALSO

78       mail(1), aliases(5), forward(5), sendmail(8)
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80       IETF RFC 5322 ⟨http://www.ietf.org/rfc/rfc5322.txt⟩
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844.2 Berkeley Distribution         2023-02-05                       mailaddr(7)
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