Oh . . . .
When you make a post, down under the text you type are 2 tabs, the first is Options - if you look down you will see a check box with a check in it titled
Notify when a reply is posted This is you watching this
thread. Make sure that box is unchecked and you won't receive emails every time someone adds to that thread/topic.
Also, there is a button down near the
Reply &
Bookmark buttons, called
Watch Forum or
Stop Watching If you select to 'watch' you will get emails for every thread posted in that forum. Click Stop Watching (if available) and you will no longer receive these email notifications.
Let me know if you have any trouble getting the settings just how you would like.