Last week I studied many Windows-Mail User Agents with the conversation
threading feature.

None of them (SUP, mutt-kz(notmuch), Outlook 2010, Thunderbird with
conversation thread plug in, Postbox, Evolution) could cope with the
following case:

 

In our e-mail-discussions people often choose 'reply-all' to construct a new
message with the same reciepients.

They clear the body and the subject, but the hidden References: and
In-reply-To: stay and should be cleared as well.

Result is that this new subject drowns in an old
conversation-thread-drilldown and this unpredictable behavior makes
conversation threading useless.

This weekend I went analyzing the notmuch-source to find where I could put a
fix best.

 

I think of a fix that indexes the first dates of (stripped) subject-changes
within threads, and with each first (stripped) subject change check the body
on quotes of previous messages. If there is no quote to referenced mails
then drop the reference and assign a new thread_id_ to the (stripped)
subject.

 

After two days of studying I think the best place with the least
interference with existing code is between 'notmuch new' and starting the
MUA. Then the threads are in place in XAPIAN, and new thread_id_'s can be
inserted.

 

Am I right?