Not sure if it's the only way, but if you click and open one of the e-mails it gives you a link inside (should be the second one) that takes you to a control panel that lets you select e-mail options or unsubscribe from them completely.
Yep thats how you do it! But beware. If you post blogs forums and replys I dont think you get a return that something is going on if your getting answers to the replys and comments. It gets kinda hard keepin up with stuff if you got several goin on.
But why do it? I get e-mails on the things I comment on. I like that because I was interested in it enough to comment in the first place. I want to know when someone else has an opinion about the same subject. Even if it's a year later.