I find it hard to follow up on ticket notifications sent via email, because they cannot be grouped by thread. There are two reasons for that:
* there is no In-Reply-To header in any of the emails, making automatic grouping impossible
* the subject line changes all the time, so I'd need to group emails by regular expression. That's very tedious.
If possible I would like the emails to include the In-Reply-To header, so that email clients can properly group the messages in threads. That's a very simple change and it would help a lot.
