MAILADDR(7) Miscellaneous Information Manual MAILADDR(7)
mailaddr - mail addressing description
Mail addresses are based on the ARPANET protocol listed at the end of
this manual page. These addresses are in the general format
where a domain is a hierarchical dot separated list of subdomains. For
example, the address
is normally interpreted from right to left: the message should go to
the ARPA name tables (which do not correspond exactly to the physical
ARPANET), then to the Berkeley gateway, after which it should go to the
local host monet. When the message reaches monet it is delivered to
the user ``eric''.
Unlike some other forms of addressing, this does not imply any routing.
Thus, although this address is specified as an ARPA address, it might
travel by an alternate route if that was more convenient or efficient.
For example, at Berkeley the associated message would probably go
directly to monet over the Ethernet rather than going via the Berkeley
Abbreviation. Under certain circumstances it may not be necessary to
type the entire domain name. In general anything following the first
dot may be omitted if it is the same as the domain from which you are
sending the message. For example, a user on ``calder.Berkeley.ARPA''
could send to ``eric@monet'' without adding the ``.Berkeley.ARPA''
since it is the same on both sending and receiving hosts.
Certain other abbreviations may be permitted as special cases. For
example, at Berkeley ARPANET hosts can be referenced without adding the
``.ARPA'' as long as their names do not conflict with a local host
Compatibility. Certain old address formats are converted to the new
format to provide compatibility with the previous mail system. In par-
is converted to
to be consistent with the rcp(1C) command.
Also, the syntax:
is converted to:
This is normally converted back to the ``host!user'' form before being
sent on for compatibility with older UUCP hosts.
The current implementation is not able to route messages automatically
through the UUCP network. Until that time you must explicitly tell the
mail system which hosts to send your message through to get to your
Case Distinctions. Domain names (i.e., anything after the ``@'' sign)
may be given in any mixture of upper and lower case with the exception
of UUCP hostnames. Most hosts accept any mixture of case in user
names, with the notable exception of MULTICS sites.
Differences with ARPA Protocols. Although the UNIX addressing scheme
is based on the ARPA mail addressing protocols, there are some signifi-
At the time of this writing the only ``top level'' domain defined by
ARPA is the ``.ARPA'' domain itself. This is further restricted to
having only one level of host specifier. That is, the only addresses
that ARPA accepts at this time must be in the format ``userAThost.ARPA''
(where ``host'' is one word). In particular, addresses such as:
are not currently legal under the ARPA protocols. For this reason,
these addresses are converted to a different format on output to the
Route-addrs. Under some circumstances it may be necessary to route a
message through several hosts to get it to the final destination. Nor-
mally this routing is done automatically, but sometimes it is desirable
to route the message manually. An address that shows 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. This path is forced even if there is a
more efficient path to hostc.
Route-addrs occur frequently on return addresses, since these are gen-
erally augmented by the software at each host. It is generally possi-
ble to ignore all but the ``user@host'' part of the address to deter-
mine the actual sender.
Postmaster. Every site is required to have a user or user alias desig-
nated ``postmaster'' to which problems with the mail system may be
CSNET. Messages to CSNET sites can be sent to ``user.host@UDel-
The following comments apply only to the Berkeley environment.
Host Names. Many of the old familiar host names are being phased out.
In particular, single character names as used in Berknet are incompati-
ble with the larger world of which Berkeley is now a member. For this
reason the following names are being obsoleted. You should notify any
correspondents of your new address as soon as possible.
OLD NEW j ingvax ucbingres
p ucbcad r arpavax ucbarpa
v csvax ucbernie n ucbkim
The old addresses will be rejected as unknown hosts sometime in the
What's My Address? If you are on a local machine, say monet, your
However, since most of the world does not have the new software in
place yet, you will have to give correspondents slightly different
addresses. From the ARPANET, your address would be:
From UUCP, your address would be:
Computer Center. The Berkeley Computer Center is in a subdomain of
Berkeley. Messages to the computer center should be addressed to:
The alternate syntax:
may be used if the message is sent from inside Berkeley.
For the time being Computer Center hosts are known within the Berkeley
domain, i.e., the ``.CC'' is optional. However, it is likely that this
situation will change with time as both the Computer Science department
and the Computer Center grow.
Bitnet. Hosts on bitnet may be accessed using:
mail(1), sendmail(8); Crocker, D. H., Standard for the Format of Arpa
Internet Text Messages, RFC822.
4th Berkeley Distribution MAILADDR(7)