Are you getting multiple emails for a single thread, or for all threads?
If you want to shut off notifications altogether, look at the right-hand side of the page, in your profile and community (forum) settings are. Click Email Notifications. You'll navigate to a page where you can uncheck Receive Email Notifications.
When I post a reply to a thread, I'll uncheck the option to receive notifications for replies to that post.
Offhand, I'm not sure yet about turning off notifications for specific responses. I'll have to dig and see what I see.