Path: utzoo!mnetor!uunet!mcvax!ukc!dcl-cs!strath-cs!jim
From: jim@cs.strath.ac.uk (Jim Reid)
Newsgroups: comp.mail.headers
Subject: Re: RFC976 vs. the real world...
Message-ID: <754@stracs.cs.strath.ac.uk>
Date: 2 Dec 87 12:51:51 GMT
References: <18533@amdahl.amdahl.com>
Reply-To: jim@cs.strath.ac.uk
Organization: Comp. Sci. Dept., Strathclyde Univ., Scotland.
Lines: 40

In article <18533@amdahl.amdahl.com> tron@uts.amdahl.com (Ronald S. Karr) writes:
>Some Introduction:
>However, we have conflicting ideas concerning what to do with sender
>addresses in headers.  We do, now, support the idea that a pure !-path
>coming in can be left as a !-path, with the current hostname prepended
>(this is optional and is a function of the destination).  However,
>should I ever produce, in mail originated locally, a From: line in the
>following form?
>
>	From: localhost!username

The answer is perhaps. In an ideal world, everyone will adhere to one
standard for mail headers - RFC822 possibly, but X.400 is more likely.
Until that glorious day arrives (if it ever does), mailers at the mail
'gateways' between networks will have little option but to munge
addresses because of incompatible mail headers and addressing formats.

What you mail system should do is rewrite mail headers into the
appropriate form for transmission to a given host. In short, if your
uucp neighbours only understand bang-style addresses, you mailer should
only present bang-style paths to these sites. If some sites understand
RFC822 (user@host.domain), then you should send them RFC822 style mail.
What would be less easy for the mailer is separating your bang-stlye
uucp neighbours from those who understand RFC822.

The best mailers (MMDF or sendmail - no flames please!) take an input
address, convert it to a canonical form and then rewrite the address in
the appropriate style for the message transfer agent. This is the most
sensible way of dealing with hybrid addresses like A!B@C. [Does that
mean send by uucp to A for relaying to user B on host C or does it mean
send to C for them to relay to user B on uucp host A? Then what if C
(or A) doesn't like addresses with '!' (or '@') signs in them?]

		Jim
-- 
ARPA:	jim%cs.strath.ac.uk@ucl-cs.arpa, jim@cs.strath.ac.uk
UUCP:	jim@strath-cs.uucp, ...!seismo!mcvax!ukc!strath-cs!jim
JANET:	jim@uk.ac.strath.cs

"JANET domain ordering is swapped around so's there'd be some use for rev(1)!"