When you open up a thread (topic), you will see a drop down menu at the top right hand corner of the thread, titled "Thread Tools."
1. Left click on that to drop the menu down.
2. The 3rd choice down is "Subscribe to the Thread."
3. Left click on that choice.
4. Above the "Add subscription" link at the bottom of that page, you will see a "Notification Type" drop down menu. If you left click on the down arrow, you will see your email subscription choices.
5. Choose the email subscription that works best for you (I think there's instant, daily or weekly) and then left click the "Add Subscription" link at the bottom of the page.
6. Enjoy your email notices.