1. Enable the Email function in the Mail Server configuration of the "Admin Options". Also, you have to choose the mail component and specify the address of your mail server.
2. Go to the "Feature Configuration" in the "Admin Options" and select there the subscription level you want to use (whole board, category, forum, topic)
3. You must turn on the subscriptions for every single category and forum you want to use them with. This is done with editing the category/forum (click on the pencil sign ] on the right side of the the categories/forums at your default.asp). There you must allow the subscriptions.
4. Then, you can subscribe to the whole board/category/forum/topic by clicking on the envelope button .
5. To view, what subscriptions you have, click on "My Subscriptions" on the top menu.