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Posting-Version: version VT1.00C 11/1/84; site vortex.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!petrus!bellcore!vortex!lauren
From: lauren@vortex.UUCP (Lauren Weinstein)
Newsgroups: net.mail.headers
Subject: Re: From: and To: in UUCP land
Message-ID: <742@vortex.UUCP>
Date: Thu, 15-Aug-85 13:48:49 EDT
Article-I.D.: vortex.742
Posted: Thu Aug 15 13:48:49 1985
Date-Received: Sun, 18-Aug-85 05:09:33 EDT
References: <835@plus5.UUCP>
Organization: Vortex Technology, Los Angeles
Lines: 41

1) There is nothing wrong with putting @'s in the transport layer
   if you know that the site you're sending to can handle it
   properly.  I keep tables with such knowledge, so that I can choose
   ! or @ routing as appropriate, based on my knowledge of the hosts.
   For example, ihnp4 can handle addresses like user@site.UUCP, so
   I can send them that way for domain-based mail that I'm sending
   to ihnp4 for non-local resolution. 

2) @'s in the To: and From: lines are the ONLY way to maintain
   822 compatibility with the outside world, and many smaller
   machines with limited software are starting to act as gateways
   and can't be expected to do @/! conversion.  I see nothing wrong
   with @'s in the To:/From: lines so long as the From_ line is valid
   as a reply address.  In the long run, the clue that a site SHOULD NOT
   futz with the From: line (except in certain gatewaying situations)
   is the presence of the @, except in certain obvious internet
   gatewaying situations.  My own view is that due to various munging
   going on, it is important to support replies to both the From:
   and From_ line as necessary, and to send failed mail to the return
   addresses derived from internal spool files instead of header parsing.

   My own decision is to generate my From: lines in @ form, and to
   generate the To: lines in whatever form best resolves the message
   as posted by the user.  I also allow replies to either the From_
   line or the 822 lines.  In the latter case, I follow the rules
   for Sender:/Reply-To:/etc.  In the former case, I do a straight
   UUCP reply, but if an @ is present (on the From_ line) I give the
   !'s precedence (instead of the @, which has precendence on 822
   lines).  

   As a practical matter, even in our extremely mixed-up current
   environment, I find that I can successfully reply to 99+% of mail,
   through gateways and local nets, automatically, regardless of the
   smart or "dumb" hosts in the way.

3) As a general rule, I discourage the use of @'s in From_ lines,
   but when they occur I've found that my solution in (2) above
   works as a practical matter in the great majority of cases.

--Lauren--