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From: lauren@vortex.UUCP (Lauren Weinstein)
Newsgroups: net.mail.headers
Subject: Re: Mail Header Summary Document...
Message-ID: <842@vortex.UUCP>
Date: Fri, 18-Oct-85 16:06:25 EDT
Article-I.D.: vortex.842
Posted: Fri Oct 18 16:06:25 1985
Date-Received: Sat, 19-Oct-85 08:21:38 EDT
References: <2297@ukma.UUCP>
Organization: Vortex Technology, Los Angeles
Lines: 43

Gateways have special responsibilities, but even the ones that
try to modify the From: lines now often make matters worse.  Throwing
an address like: 

From: foo@bar.UUCP

at the typical ARPA site doesn't do it too much good YET.
But this will change (see below).  In the meantime, some gateways
are trying to deal with the problem in our current hybrid
situation with varying levels of success.  Eventually, ARPA
people should be able to reliably reply to gatewayed addresses like
foo@bar.UUCP without any From: modification taking place at the gateways
at all.  In any case, I don't object too strongly to a smart site taking
a !-only address (no @'s; not already in domain form) and turning it into
a simple domain address (not a route).

What causes the problems is sites that try to create From: lines
in ! form based on the existing From: line (which may contain !'s,
@'s, or both [hybrid]).  These new ! or hybrid based From: lines are 
often misleading or totally incorrect.  If they were created totally
from From_ info and didn't use the original From: line as a starting
point such problems would be reduced, but these sites often even
take perfectly valid domain-based @ addresses and modify them into
inaccurate !-paths (as I discussed in my previous message).  This
causes particular confusion on !-only paths, but in general
can cause confusion for any sort of path.

Now, in the interests of mail working in our current hybrid environment,
there are ARPA sites that do limited From: modification for some sites, but to
do it "right" they have to use the From_ routing instead of the existing From:
line as a base for creating the new line if they are more than 
one !-hop away from the message
originator.  If the message already has a domain form address, even
these gateway sites will ultimately want to leave the address completely 
alone once we have a more fully domainized environment, at least as far
as the gateways are concerned.

This matter is complex enough that I'll have to generate a longer
discussion in more detail when I can dig up some time.  There are
issues of dealing with the current hybrid environment vs. the
approaching domain environment that enter into this at various levels.

--Lauren--