Hmm...I'll have to check it out. I've been wondering about it too.
I have it checked on this topic. So I should get it if you someone else posts a message.
I do have it setup that you will only receive one email until you visit the thread again. Then it resets to allow another email. This way your inbox doesn't get overloaded. Imagine if you were subscribed to the 1/16 Tiger I Group Build (700+ replies) and you were notified whenever a post was made. [:0]