I think disallowing form email just makes it so the "email" link won't show up below your profile.
Unfortunately if you subscribe to a very active thread and browse the forum a lot throughout the day, the system will see that you are on and then off, then send you a note, then think you are on, then off, then send you a note, etc.
What I do is filter all my notifications to a specific folder and then sort those by subject so they are grouped together. Sometimes I also won't subscribe to a thread until after all the excitement has died down and I just want to get updates if it pops up again.