Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!oliveb!pyramid!hplabs!hpcea!hpfcdc!hpfclp!diamant
From: diamant@hpfclp.HP.COM (John Diamant)
Newsgroups: comp.mail.headers
Subject: Re: ! and @ -- which RFC ?
Message-ID: <7260005@hpfclp.HP.COM>
Date: 3 Apr 88 09:29:28 GMT
References: <12774@brl-adm.ARPA>
Organization: HP SDE, Fort Collins, CO
Lines: 19

> If you have the address <aaa!bbb@ccc.uucp>, 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?

You are right about the correct interpretation.  RFC822 and RFC976 are
the places to look.  By RFC822 terminology, anything to the left of the
"@" that is not a recognized routing character by the standard ("!" is
not) is part of the local part.  That gives ccc precendence.  RFC976 says
that you should never have mixed addresses, but in case you do, the "@"
has precedence (to maintain compatibility with RFC822).  The right answer
is to use "@" precedence when there is an ambiguity, but to never generate
a mixed address yourself.


John Diamant
SDE				UUCP:  {hplabs,hpfcla}!hpfclp!diamant
Hewlett-Packard Co.		ARPA Internet: diamant%hpfclp@hplabs.HP.COM
Fort Collins, CO