I just signed in to the forum with a new account name, just to make sure and it is working as expected. Receiving e-mail is easy.
Let's say you want to receive e-mail for any topic thread in the DIY Solar Experimentation & Performance section. Simply navigate to that section of the forum and click the Subscribe link at the bottom (I've added a red line pointing to it below). You'll receive e-mail for any content for any of the listed subjects.
But, what if you are only interested in one of the subjects? Not a problem!
For example, if you don't want e-mail for all the Solar Experimentation & Performance topics, but you do want e-mail for the Side by Side Testing for Hot Air Panel thread, just navigate to that thread and again click the Subscribe button. That's it!
Again, we have all the benefits of e-mail, plus all the advantages of the forum!