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From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: comp.mail.misc
Subject: Re: Which headers may Sendmail re-write?
Message-ID: <1990Dec8.051401.26836@mp.cs.niu.edu>
Date: 8 Dec 90 05:14:01 GMT
References: <1CE00001.914g2o@tbomb.ice.com>
Organization: Northern Illinois University
Lines: 56

In article <1CE00001.914g2o@tbomb.ice.com> barnett@crdgw1.ge.com writes:
>
>Reply-able? By what? If it is the user agent that incorrectly builds
>the reply address, then it is a bug in the user agent, and should
>be corrected by aliases or code fixes/extensions.
>
 Replyable by user software.  I want my users to be able to hit the 'R'
key to generate a reply with valid addresses extracted from the headers
of the mail they are responding to.

>This conversion can be done, and the delivery completed, without the
>modification of the mail's header. Do it in the sendmail "talk". If
>the conversion needs to be 
>
 Anything done which doesn't touch the headers obviously cannot fix
broken headers.  But it is the header address you are supposed to reply
to.

 Some people are purists, and have a definition of perfection which is
hardly ever met.  Others of us just want mail to work, our users to be
happy, and as little failed mail as possible.  You can complain all
you like about the idea that this should be done by the user agent, not
the transfer agent.  But if your user agent prepares bad addresses it
is my users who suffer, and my time that has to be spent explaining to
them how to prowl through the 'Received:' lines to try to construct a
possibly valid address.  And since users can create their own MUA with
some shell scripts, you will never fix them all.  But most mail goes
through a single MTA, so correcting headers there is much more likely
to be effective.

>I do not profess to be an internet mail expert, I am not. I have simply
>always thought that the problems sendmial is "solving" could be solved
>while still observing the "do not touch the letter contents" rule.
>
 Herein lies the crux of the argument.  The argument that the MTA should
not 'touch the letter contents'.  This all depends on the definition of
contents.  If you just define the 'contents' to be everything below the
header, then this is pretty well what happens.

 Part of the problem is with terminology such as 'Envelope' that has
developed.  This makes one think of a standard letter, with everything
not in the envelope being the contents.  This is an unfortunate way to
look at it.  Consider a priority mail which you are sending by
Federal Express.  Inside the package is the contents.  On the outside
of the package there is addressing information, receipts, etc.  In addition
the driver of the delivery truck has a check list he uses to keep track of
what he is delivering.  The 'envelope' of email really corresponds to
the driver's checklist.  The headers really correspond to what is on the
outside of the package.  The text below the headers correspond to the
contents of the package.

-- 
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  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115.                                  +1-815-753-6940