Notes on profile options from the temp boards: Xenforo seems to like sending alerts for everything. To shut off alerts that you don't want,, hover your cursor over your username at the upper right. You'll see a section for Alert Preferences. Click on that and you can turn off any that you don't need. You can set other profile settings using the same method. You can also get to Alert Preferences by hovering over 'Alerts' in the same area. You might also notice that xenforo will automatically have you "watch threads" for any thread you post in. To turn those off as well, go up to your username and click on "Watched threads." You then will have to manually unwatch all the threads listed, but as long as you have your alerts turned off, you shouldn't receive any more. And to stop getting e-mails every time you get a new PM (or, as the system calls them, a new message in a conversation) you need to uncheck the appropriate box under "Contact Details".
I think Grimby changed it so that it automatically leaves the "watch thread" option off when people register.