When you create a post or reply there's a set of options right above the "Submit New Topic" or "Submit Reply" buttons. There's one that says "Email Notification", uncheck that box and you won't receive those emails. To get rid of it permanantly go to "User CP" at the top of the forum listing's page. Then go to "Edit Options" and there's a question about using email notification as default. Say "No" to this question and you should be good to go!
if you already did that and its still comming, go into user cp up at the top, next you want to go to edit options then scroll down the page until you come to "Use 'Email Notification' by default?" and uncheck that box.......