[Mailman-Users] Mailman is rewriting Message-Id

Stephen J. Turnbull stephen at xemacs.org
Wed Nov 13 17:50:03 CET 2013

Roel Wagenaar writes:

 > Seems to work fine, unfortunatily mailman is rewriting the Message-Id of the
 > injected emails.

Seems very unlikely to me.  The code you propose changing should
prevent that already.  How did you determine that Mailman is rewriting
the Message-Id?

I suspect that what is actually happening is that you have an MUA that
does not set Message-ID and you are CC'ing yourself to check.  Somehow
the message gets to Mailman without a Message-ID, so Mailman (or
something before Mailman in the process) adds one to the post it
distributes, and something (probably your MTA on the way back in to
your mailbox) adds one independently to the CC that you receive.

There are several other possible explanations (besides Mailman
altering an existing Message-ID, which can't be completely ruled out
but I'd bet a euro against a yen that something else is doing it), as
well, but you haven't given enough information to diagnose the issue.

 > Is it save to alter /usr/lib/mailman/Mailman/Message.py so that the section:
 >         if not self.has_key('message-id'):
 >             self['Message-ID'] = Utils.unique_message_id(mlist)
 > is changed into:
 >         if not self.has_key('message-id'):
 >             self['List-Message-ID'] = Utils.unique_message_id(mlist)

No, it's not safe.  Messages really should have a message ID according
to the RFCs, and if Mailman receives a message without one, it should
add one.  Lack of a Message ID will mess up threading in archives and
MUAs, as most likely each downstream recipient will get a different
Message ID, just as you do.

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