@andreippo, @joop.stringer
You may have better luck starting your own thread on this one. I had a similar problem, in that users see notifications (the little icon on the wordpress nav bar) but never get an email. I will mention that if you look closely at the ticket referenced and if you do have access to the code yourself you can find the line to examine in bbpress\includes\common\functions.php -> Line 1066 and roughly 1106. My smtp provider was not liking the noreply email address that was being constructed as the sender. I changed the lines I mention to a valid email address and everything started to work. Also worth mentioning, I am using WP Mail SMTP.
