organize by conversation not working as expected
I've been upgraded to Lion for about 6 months, but only started using Mail in the last few weeks (switching from Outlook), so I don't have a lot or previous experience with Mail. Based on a colleague who uses Mail in Snow Leopard, it appears that the "organize by conversations"/threading doesn't work like the version of Mail in Snow Leopard for some specific email that I receive.
My office uses Request Tracker (RT) for ticketing. The emails I receive from this system get threaded by the sender and subject for a given ticket, and not just by the subject, regardless of sender. This isn't occuring for any other emails I receive (at least that I've noticed so far). I end up with multiple threads for the same subject. Here's a screenshot, probably easier to see it (apologies for the major whitewashing, but this is only something I use at work, trying to eliminate anything salient - the subject is identical in all of these)
In all of these cases, the email is being sent on behalf of the user by RT, and the from is something like "Chris Fabri via RT <email@some.domain.com>" The reply to will be that same From email address as well. So the From and Reply-to fields are the same for all three threads above In the older version of mail a colleague is using, the above would all be one thread. Additionally, RT has a "reply" and "comment" email. Comment is an example of above, and the reply is email-comment@, and thee reply is just email@, and there is no "<cmt>" in the subject. The Snow Leopard version is able to thread both the reply and the comment emails into one thread (I've actually yet to see another client do that). It seems that with the new version, threading is making some additional decisions that's resulting in the multiple threads to what would otherwise by the same subject.
Is this a change in the inherent behavior of Mail 5.2? Is this something that can be configured? I've not been able to find any guidance if it's the latter. I'm hoping that somebody else has maybe seen this behavior as well for some different set of emails.