I've been asked once or twice about how to turn these off.
You have 2 options:
1/ If you just don't want an email to say there's been a reply to some posts, but do on others, then before you click 'Send' on the post, just below the 'Send' button is an 'Options' area (if it's not open just click the '+' in the right hand corner), then untick the 'Notify me when a reply is posted' button & you'll get no email when there is a reply.
2/ if you want to stop all the emails letting you know when you get a reply, then click on the 'profile' button above, then the 'Preferences' tab, then the 5th one down that list is ' Always notify me of replies :' click the 'No' button, then press 'Save' at the bottom of the page & you're done.
I personally set up a new folder (or 'label' in gmail) & created a rule so that any mail from "board@forumotion.com" (don't include the "") goes straight to that folder, that way I can know when people reply to a post I posted on, but I don't have my main inbox cluttered with mail from the board.
If anyone needs any extra help sorting out this issue let me know & I'll do what I can to help you sort out any issues