To: "Jack De Winter" <jack@wildbear.on.ca>
cc: drums@cs.utk.edu, jgm+@cmu.edu, mrc@panda.com
Subject: Re: regarding the handling of weird address formats. 
In-reply-to: Your message of "Wed, 30 Oct 1996 13:51:09 EST."
             <19961030135109.00c69ce8.in@lacroix.wildbear.on.ca> 
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Date: Wed, 30 Oct 1996 11:47:33 -0800
From: michael.derrico@software.com (Michael D'Errico)
Message-ID: <19961030194914348.AAA594@bonn.software.com>

> Take one that I got this morning:
> 
> From ietf-announce-request@ietf.org Wed Oct 30 10:54:05 1996
> To: IETF-Announce: ;@wildbear.on.ca
> cc: atommib@thumper.bellcore.com
> From: nobody@wildbear.on.ca
> Date: Wed, 30 Oct 1996 10:54:04 -0500
> Subject: None
> 
> Now, I have been told be one half of the people that I should not rewrite
> headers and the other half that says it is my responsibility to make sure
> that any messages I pass forth are RFC822 compliant.  So, I choose the
> worst case (doing something that may be considered wrong, but ends up with
> a result that is desireable, versus passing an undesireable message along).

Strictly speaking, an MTA should not add any headers except for Received.  
Most MTAs violate this to some degree, however, because some users appear to 
benefit from the header rewriting.  My personal belief is that you should 
pass whatever you get intact, otherwise you run the risk of doing something 
wrong (such as what you did to the above header), leading to user confusion 
and a less-robust Internet.

> So, when I get this message, it does not seem to have a Subject or a From
> line, so I add default ones.  The To line also seems to be a problem, as
> I believe it was something of the form

Don't ever add a Subject: line.  "Subject: None" provides absolutely no 
useful information for the recipient.

You shouldn't add From: if it's not there, especially if the message didn't 
originate from a local domain (ietf.org is not yours).  And if you do want to 
put in a From: header for some reason, at least pick a real address such as 
the envelope sender (in this case ietf-announce-request@ietf.org).  Oh, and 
you should really put it in Sender: instead of From:....

> To: IETF-Announce: 
> 
> Is this going against the RFC822 or RFC822bis designs?  If not, and someone
> else out there is getting different headers, can you all tell me the right
> way to parse it?

It was "To: IETF-Announce: ;" which is legal according to RFC 822; it is 
known as a group construct.  This particular one has no addresses in the 
group since the list administrator doesn't want to have any recipients listed 
in the header, but RFC 822 requires one of To:, cc:, or bcc: to be in the 
header.

> How bad is it to actually change the headers so that they
> are RFC822/822bis compliant?

You turned a valid To: header into an invalid one.  That's not acceptable.

Mike