When you reply to a message you'll see that over on the right hand side of the text box there's a checkable option called 'Email me when someone replies'.
By selecting that option you'll be notified automatically on every reply.
BUT... it can bloat your email box if it's a hot topic. I've seen ten or fifteen email notifications come in all at once.
In order to shut this off you'll need to go to your personal page and go to My Settings. Go to "Subscriptions & Bookmarks".
There you'll find all of the threads that you've opted to receive emails about. To shut down the email notifications you'll select the box to the left of your desired targets and then click on the 'EMAIL SUBSCRIPTIONS OPTIONS" dropdown box that's right above the gray line.
Select DELETE and it'll remove your chosen selections from your email list.
ON? Easy.
OFF? Also easy.
