It's not what you think. Email notifications only let you know when there is a new post. Not when someone mentions your name or quotes your post.
This, although when it worked best, it would send me a new email if I read the email, yes, somehow mmo-champ would know. I bet the email provider would tell mmo-champ that the email has been opened, thus mmo-champ automatically sends another reply email for the next.
There were also times when I'd get emails for every reply. I prefer for after I look at the most recent post or open the email, personally.
Still, doesn't explain why I stopped getting the emails. =/