Strange as it may sound to you. I have no idea where it is going. I could also say nothing has changed for me in a long long time with spam handling in Thunderbird. But I do not have an antivirus program that thinks it should be involved in SCAM and SPAM filtering? Does yours try and fail perhaps?

Matt, Thanks for the reply. I do have a security program that busies itself with spam, but it is limited to writing that it thinks a message is spam or scam in the header. Thunderbird can normally take these modified messages to the junk folder. It can also take spam that hasn't been flagged to junk. Thunderbird has put thousands of flagged messages in junk, so I don't think that's the problem.

Today Thunderbird put two spam messages in junk, but it said it was putting further messages there and they just disappeared,

Alan.