What is the basis for e-mail notifications? I notice that I haven't received e-mail notifications for some threads, while I receive notifications for other threads. Sets me thinking....
Look at the bottom of this page.
If you see a clickable link that says: "Watch this topic for replies", that means you will NOT be receiving email notifications for the thread until you click on that link.
If you see a link that says: "Stop watching this topic", that means you are currently receiving email notifications for any replies to the thread, until you click on that link.
When you make a post, you can set the check box on "Notify me when a reply is posted" to determine if you want to receive email notifications or not for that specific post.