[Mailman-Users] Mailman reusing message-id, leads to duplicate message suppression

Ralf Hildebrandt Ralf.Hildebrandt at charite.de
Wed Nov 6 09:51:00 CET 2013

* Stephen J. Turnbull <stephen at xemacs.org>:

> Note that the subject is incorrect.  Mailman is not reusing the
> Message-ID, it is refusing to alter it which is correct behavior
> according to RFC 5322 (Message-ID is an originator field).
> I believe that according to RFC 5322 (and predecessors) Mailman SHOULD
> add a Resent-Message-ID to indicate that it handled the message, but I
> doubt this would change the duplicate-suppression behavior of Gmail
> and MS Exchange.

I agree. The duplicate-suppression in Exchange uses both "Message-ID"
and "Date" headers.

> Footnotes: 
> [1]  It's surprisingly difficult to handle duplicates truly gracefully.

Ohhh yes.

> For example, I personally consider the mailing list copy to be the
> "canonical" copy of a post, but direct CCs often arrive more quickly.

Same here. Happens all the time.

Ralf Hildebrandt                   Charite Universitätsmedizin Berlin
ralf.hildebrandt at charite.de        Campus Benjamin Franklin
http://www.charite.de              Hindenburgdamm 30, 12203 Berlin
Geschäftsbereich IT, Abt. Netzwerk fon: +49-30-450.570.155

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