After registering, you may start receiving email notifications stating someone has replied to your post.
To stop the emails, click on "Your Stuff" in the nav bar, then click on "Preferences."
From there, you can control what emails you wish to receive. This is a global change and will affect all your posts from that point on.
To change your email preferences from thread-to-thread, located in the right column is an "Actions" box. From there you can control whether you wish to receive emails specifically for that thread.
At this time, the global changes to email preferences is on a go-forward basis, meaning if you are receiving email notifications from a specific thread and you then turn off the notifications globally, you will still receive emails from that thread.
You need to turn it off at the thread level as well.