Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!nrl-cmf!cmcl2!brl-adm!adm!netinfo%garnet.Berkeley.EDU@violet.berkeley.EDU
From: netinfo%garnet.Berkeley.EDU@violet.berkele (Postmaster & BITINFO)
Newsgroups: comp.mail.headers
Subject: Re:  ! and @ -- which RFC ?
Message-ID: <12803@brl-adm.ARPA>
Date: 5 Apr 88 01:03:55 GMT
Sender: news@brl-adm.ARPA
Lines: 93

In reply to:

	X-Msg-Id: <02104116_CU00>
	Date:     02 Apr 88 10:17:00 EDT
	From: Walter Roberson 
	To: 
	Subject:  ! and @ -- which RFC ?
	
	Someone has recently asked me where the 'rule' governing the
	interpretation of '!' and '@', both in the same address, may be
	found.

"xxx!yyy@zzz" is interpreted differently in UUCP mail and Internet
mail. In UUCP addresses the "!" takes precedence, in Internet mail
addresses the "@" take precedence.  This can be confusing to Internet/
UUCP hosts unless the appropriate address conversion is done going
both in and out of the local mail transport system. There are also
separate address conversion rules for addressees (To, Cc, etc) and
originating addresses (From, Sender, etc.). And a separate sets of
rules for each type of mail network address handled by the mail
gateway (mail exchanger).
	
	If you have the address , should
	this be interpreted as aaa!bbb!ccc or ccc!aaa!bbb ? As far as I
	know, the latter is correct -- but that is simply my experience,
	and not something I've seen documented. Could someone please
	point me to the appropriate RFC or other document?
	
	   Thank you,
	
	   Walter Roberson 
	
I believe ucbvax.berkeley.edu was the first to implement the
aaa!bbb@ccc.UUCP local addressing convention.

You will find it documented in the mailaddr(7) section
of the "Unix Programmer's Manual, 4.2 Berkeley Software Distribution,
Virtual VAX-11 Version" dated August 1983 and in Unix manuals based
on BSD Unix.

QUOTE

     Compatibility. Certain old address formats are converted to
     the new format to provide compatibility with the previous
     mail system.  In particular,

                    host:user

     is converted to

                    user@host

     to be consistent with the rcp(1c) command.

     Also, the syntax:

                    host!user

     is converted to:

                    user@host.UUCP

     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 mail system which hosts to send
     your message through to get to your final destination.

UNQUOTE

UUCP mail now supports "domain" instead of "host" at many sites.
So this manual section is out-of-date. The new UUCP address convention
is "domain!user" or "uucp-host-domain-list!domain!user".

On an Internet mail host that is a UUCP gateway the local address
 should be converted UUCP address "ccc!aaa!bbb"
for messages being send to UUCP.  If going to an Internet site,
that local UUCP address be converted to the Internet mail address:
 where "gateway-domain-name" is
a valid internet domain name. Note that these rules are for
addressees (To, Cc, etc.) only. 

Bill Wells, Postmaster

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