I have noticed that the flagging / marking has nothing to do with the message actually making it to your inbox or junk folder. I periodically look at my junk folder, just to see if something got trapped, and I always find obvious phishing / scam emails that are marked as "Safe". I would like to see a way to report these to Avast so that the system can get better. Unfortunately, like most algorithms, it is only as good as the data that it has... or a list of known bad actors.