This forum system can operate like a mailing list (like Yahoo Groups) or like a web forum.
It doesn't matter where you post, the messages will get through the same way. You can also use both methods (so you can use the web at work, and use email at home if you wish).
At the top of this page is a button marked "Forum Sunscriptions". If you click it, you can see all of the forums - if you subscribe to one, it will be delivered to your email address, and you can participate in the discussion by email, just like Yahoo Groups.
If you don't want to use email, don't worry - you won't miss anything.
The Forums and Email lists update every fifteen minutes or so (more often if there are a lot of new posts).