If you go to your User CP, then click on Edit option, there is an option to have threads you are subscribed to sent to your email when there is a reply there
It is under this headingefault Thread Subscription Mode. I have mine set to daily email notification, and every night the emails come through for each thread I have posted on.
Hope this helps!
Also if you click on active topics you should see a green check mark on each thread you have made a post in. In about the center of the screen where the field goes from white to grey.