I also have the problem. I'd like to get only emails for new topics on selected forums and for threads where I'm involved.
Not an email for every posting someone makes to a thread.
I think I replied to this in another thread, but currently there is no way via email to only get new topics. The best way to do that right now is the use the RSS feed option for a space. RSS feeds only show new content.
FWIW, I've had complaints on the other side that RSS doesn't support all updates and replies, so we'll work with our provider to see what other options there are.
Thanks for the feedback,