I don't know if you have any control over how the forum software works (I suspect that you don't, but it can't hurt to ask), but if I subscribe for email notification of new messages in a thread, it appears that no notice is sent if a message in the thread is edited, which often is just as significant as a new message. (I just stumbled across one which I otherwise would not have known about since no notice was sent.) If there is any way to make that happen, it would be great.