It seems that even after upgrading to 1.6.4 latest build as of right now email notifications have some strange behaviour.
After rigourous testing with some friends it seems all notifications will go out except to the email that is set in your own user profile.
When I changed my email address in my personal profile the system would no longer send notifications to the new address but would now send them to the address that it was not sending to before that.
So email notifications are working but wont send to the address you have set in your profile.
I think that is a bug? Do you guys agree?