I am in the same boat. I ended up setting a mail filter in Gmail to archive and move all the discussions to a new folder. Keeps the notifications out of my in-box, and I can look at if interested as well.
You should also check the individual discussion threads and the spaces they are in to verify you haven't turned on the email notifications there. This is separate controls from the preferences under your community username profile.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.