Threading is foobared?

[Mark Sapiro]

Hi all,

I'm jumping in on this thread because Tim asked.

I'm here because I'm a Mailman developer and the primary maintainer of
Mailman for the @python.org lists.

Regarding the initial post in this thread from Steven D'Aprano
suggesting that broken threading is more common recently and quoting a
couple of Message-ID:/References: headers wherein a message ID was
apparently munged from

<1392737302.749065.1459024715818.JavaMail.yahoo at mail.yahoo.com>
to
<1392737302.749065.1459024715818.JavaMail.yahoo.ref at mail.yahoo.com>

Some Background:

Our long time mail.python.org server provided by xs4all died of severe
hardware failure late last October. We were able to get a replacement
server through the PSF and get it configured and running within a couple
of days, but this new server couldn't access the nntp server at xs4all.
With the kind assistance of members of the community we were able to get
access to a news server at the Free University of Berlin which is now
our gateway to Usenet.

This server undoubtedly has different policies and behaviors from the
prior server at xs4all. I'm not sure what mail or news server is
responsible for munging the IDs as above, but it could be our new Usenet
gateway. All I know for sure is that Mailman doesn't do that specific
munging.

What Mailman does do as noted by Random832 is replace the Message-ID:
header value in posts gated to Usenet with a list specific, Mailman
generated unique value. There is a reason for this, and that reason is
if a message is cross-posted to two lists which both gateway to Usenet,
and Mailman didn't make the Message-IDs unique, the news server would
discard one of the two posts as a duplicate and the post would be
missing from one of the recipient Usenet groups.

Granted that this is bad and breaks threading, but avoiding message loss
is a more important goal.

I understand I'm not providing any solutions here, but perhaps a more
complete understanding of what the issues are will ease the pain.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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