Actually I don't know / remember if the email system is correctly working on the forum, seems like we can actually receive emails, but, can we "reply via email" ? if this feature stopped to work maybe a lot of people lost their posts trying to answer from email? 
Any volunteers to do these tests?:
Test 1: if you used this feature in the last 30 days, you should have a copy of that email in your email "sent" section, just check it and make sure your reply was published on the forum (same thread, etc...)
Test 2: A mention B, but B doesn't enter in the forum in the next 1 hour (i think), which then should receive an email notification about the mention, then reply the email, 5 minutes later check if the reply is posted in the forum
