From: cos@leftbank.com (Ofer Inbar)
Message-Id: <9603111743.AA28009@leftbank.com>
Subject: Re: Message format document outline
To: drums@cs.utk.edu
Date: Mon, 11 Mar 1996 12:44:00 -0500 (EST)
In-Reply-To: <199603110654.BAA20559@wilma.cs.utk.edu> from "Keith Moore" at Mar 11, 96 01:54:40 am
Organization: The Left Bank Operation - http://www.leftbank.com/
Reply-To: cos@leftbank.com
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Several years ago I began writing scripts to process mail for mailing
lists, mail-news gateways, and the like.  I'd read RFC822, and at
first all my scripts were written to check for two consecutive line
terminations as the end-of-headers marker.  However, I soon discovered
that this was failing for some messages, and rewrote the scripts to
test for any line containing nothing but whitespace as end-of-headers.
Some of these scripts are still in use today, and this aspect has yet
to fail in any serious way.  In other words:
 a) The number of messages which had whitespace in the end-of-headers
marker was significant enough to force me to "fix" the scripts.
 b) There have been a few messages since then with blank continuation
lines (or some other "bug" has caused a blank line in the middle of
the headers), but they have been very rare.
 c) Failure to recognized end-of-headers, in the first case, would
cause a serious failure - The entire message was interpreted as
headers, resulting in many cases in the body of the message not being
forwarded properly.
 d) Failure in the second case, seeing an end-of-headers marker where
one was not intended, has never caused a serious failure.  At worst, a
Subject: or To: line ended up in the body of the message, resulting in
a message with no subject, or an Apparently-To line, messing with
people's filtering rules perhaps.  But it has never caused a message
body not to be forwarded to its destination.

Any mail software that I write today will definitely interpret the
first blank line, with or without whitespace, as end-of-headers,
because that's what works.  I think RFC822bis should say that too.

  --  Cos (Ofer Inbar)         -- cos@leftbank.com cos@cs.brandeis.edu
  --  The Left Bank Operation  -- lbo@leftbank.com http://www.leftbank.com
 "We all misuse the net for personal gain, one way or another."
    -- Larry Wall <lwall@netlabs.com>