How To Add Email Notifications
When on the thread that you'd like to receive notifications of new posts on, click on the options link and choose subscribe.
Now you need to change the subscription to an email one.
Click on edit my preferences > notifications > subscriptions.
Now click on edit under the operations column on the subscription you'd like to get email notifications of.
In the send method drop down, choose HTML Mail.
Now click save subscription. You're done. You'll now get an email any time there is a reply to the thread.