Hi hellwarrior,
If you go to the forum you're interested in, so, for instance, Ships, you'll on the right-hand side of the browser a menu titled Forum Options. From that menu you can subscribe to a Forum via email or RSS feed.
Also, you have to have email notifications turned on in your community settings.
Hope that helps. However, I caution, you may be in for more than you bargain for, especially on the more popular forums, like Group Builds.
Tim
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