limited threading in web interface to mailman/pipermail (confusing, when viewed alongside truer threading in Nabble)

[Graham Perrin]

At <http://lists.osafoundation.org/pipermail/chandler-users/2009-October/thread.html> 
there are two messages with the subject
[chandler-users] Use of Chandler as timeswitch (OBeMS)
(the user posted twice).

There, both messages are presented correctly.

Bug

In Nabble, both messages appeared in the midst of an unrelated topic.

In the footer of the first of the two received in my Inbox via Nabble:

> View message @ http://n2.nabble.com/Heavy-problems-on-PPC-Mac-tp3226043p3832986.html

In the footer of the second one received in my Inbox via Nabble:

> View message @ http://n2.nabble.com/Heavy-problems-on-PPC-Mac-tp3226043p3842766.html

Workaround

One of the two, I removed. The other, I moved to its proper place.

Question

Please, what could cause this bug?

[Graham Perrin]

I wonder whether we should merge this topic with
posts via Nabble forum 1653123 in incorrectly threaded on delivery …

[Graham Perrin]

Looking more closely, the MarkMail permalink for the thread
<http://markmail.org/thread/m4docx76tfxuwd4u> presents
John Beardmore's messages (with OBeMS in the subject lines)
in the midst of an unrelated thread (with PPC in the subject line)

I'll make a lazy guess that:

a) the user replied to an unrelated message and changed the subject line before posting

and

b) the available web interface to mailman/pipermail simply does not make the association with earlier parts of that thread.

I'm moving this topic to the resolved area.

[Hugo <Nabble>]

Graham Perrin wrote

a) the user replied to an unrelated message and changed the subject line before posting

That's correct. Nabble uses the Message-ID header of emails to find their parents (with the help of In-Reply-To header). So this can really be the cause of wrong threading. We have code to rethread mailing list archives, but if the problem is just a few messages, it is better to move them by hand.

[Graham Perrin]

Better to default to using Message-ID for threading.

Hugo <Nabble> wrote

We have code to rethread mailing list archives

If ever that code is required:

* could the re-threading apply to just part of a forum (say, messages during a defined period)

* or would it apply to the forum (list archive) in its entirety?

(I'm happy to move by hand, I usually do, but I'm paying greater than usual attention to this particular forum.)

Thanks
Graham

[Hugo <Nabble>]

The rethread process can only be applied to the entire forum.