Thunderbird marks some messages from a contact in my Personal Address Book as Junk, even though the contact is in my Personal Address Book. When I click the Not Spam button, the message briefly gets set to Not Junk, but then it gets reset to Junk when I open the message or change folders. I have set "Do not automatically mark mail as junk if the sender is in: Personal Address Book". I checked that the correct sender email address is in my Personal Address Book. I reset the Training Data. I don't see anything on my ISP (verizon.net with aol.com hosting my email) in the Spam folder. I don't know if my ISP is tagging the message as Spam. The messages are from Groupon, so I understand why they might be flagged if they were not in my Personal Address Book. Some messages from Groupon are not marked as Junk, so it seems like the adaptive junk mail controls are working otherwise. Also, I have a filter that moves Groupon messages to a folder for ecommerce. Both the Junk and Not Junk Groupon messages are moved to the ecommerce folder. When I see the Junk Groupon messages, I dutifully set them to Not Junk. How can I check a message to see if it has been flagged as Spam in the header or elsewhere (not the Junk icon)? If that is not the problem, is this a known bug in Thunderbird or a setting that needs to be changed? What can I do? I am using Thunderbird 60.7.2 (64-bit) on Ubuntu Mate 16.04. Thanks!