It may be that you are just getting emails for threads you had already subscribed to. If you go to user CP aand under the current threads, there is a button that says "view all subscribed threads". This will bring up a large number of pages. Each thread will have it's subscription status next to it. You can change the subscription status to no emails or just mark all the threads and, at the bottom of the page, select the delete threads option.
Hope this helps.
"For to be free is not merely to cast off one's chains, but to live in a way that respects and enhances the freedom of others." - Nelson Mandela