I have been using TB for years. I just discovered this morning on my W11 system, that in my message filters labeled "head hunters" that individual domain names are being deleted. This is on top of having to run rules manually to get them to take effect. Let me be clear: I capture email address and strip them to domain name, add them to the list called "headhunters" and have that set up for ending with. This way I don't have to have one for each person from that entity that contacts me. So I had at the end of last week, something like 20 entries. Today, I have maybe 10. I have been going through many reports and I am seeing similar complaints about rule elements going away, and I even got the impression one person was having Rule sets get deleted (Rule set would be a Name, which then has individual rows to act on). I have folders that have been defined to have removal of all email older than, say, 30 days. I have my inbox rule that gets rid of all emails over 400 days old. Can this set of processes somehow be in conflict so that Thunderbird is deleting elements in rule sets?