Message-ID: <c=US%a=_%p=VA%l=VHAISFHBEXC1-970908161632Z-4566@vhaishhbexc1.med.va.gov>
From: "Woodhouse, Gregory" <Gregory.Woodhouse@med.va.gov>
To: "'drums@cs.utk.edu'" <drums@cs.utk.edu>,
        "'Jacob Palme'"
	 <jpalme@dsv.su.se>
Subject: RE: Incorrect use of the word SHOULD in relation to Message-ID
Date: Mon, 8 Sep 1997 11:16:32 -0500
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I have to agree that whether or not it is possible to deliver a 
message should not be the only criterion of whether a protocol feature 
should be considered mandatory. For example, there are valid reasons 
why one host may wish to communicate the delivery status of a message 
to another. Consider the case of delivery status notifications - if a 
relay host needs to notify the sender of a message that the message is 
undeliverable it does need some means of identifying that message. 
Message IDs provide this mechanism. In fact, I would go so far as to 
say this is a situation in which message IDs are not only useful, but 
essential to the proper operation of Internet mail.

My vote is that a Message-ID MUST be present.

===
Gregory Woodhouse
San Francisco CIO Field Office - Infrastructure
Gregory.Woodhouse@med.va.gov
+1 415 744 6362

----------
From:  Jacob Palme [SMTP:jpalme@dsv.su.se]
Sent:  Saturday, September 06, 1997 11:03 AM
To:  drums@cs.utk.edu
Subject:  Incorrect use of the word SHOULD in relation to Message-ID

draft-ietf-drums-msg-fmt-02.txt says:

   Though optional, every message SHOULD have a "Message-ID:" field.

This use of the word SHOULD is not compliant with RFC 2119, which 
says:

   SHOULD   This word, or the adjective "RECOMMENDED", mean that 
there
   may exist valid reasons in particular circumstances to ignore a
   particular item, but the full implications must be understood and
   carefully weighed before choosing a different course.

In the case of "draft-ietf-drums-msg-fmt-02.txt", the reason why
this is SHOULD and not MUST is to allow compliance with some older
software which does not generate correct Message-ID fields, not
because there are valid reasons in particular circumstances to
generate messages without Message-ID.

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Jacob Palme <jpalme@dsv.su.se> (Stockholm University and KTH)
for more info see URL: http://www.dsv.su.se/~jpalme