Just in case anybody else is wondering the same thing: http://community.active.com/docs/DOC-1946

Don

After you log in, in the upper right hand section you'll see your name followed by "My Active" and "Log out".  Click on "my active", and after it loads you'll see a row of tabs.  Click on the one that says "email notifications".  After that loads there will be a list of subjects that you have answered.  Put a check mark in the box next to each one you don't want, then at the bottom of the list it says something like "...delete checked items".  Then it tells you that you have no notifications coming.

EDIT:  Just noticed a column on the right of the original post that is titled "Actions".  If it says, "Stop email notifications", click on it.  If it says, "Receive email notifications" you will continue to get the email notifications.