What if you disable those filters, on both computers? Are any of those filters deleting messages? Is the message count in Thunderbird's status bar the same on both computers?

Thanks for the suggestion. However, if the filters are identical on both machines (because they were copies of each other), why would a message show up on one machine and not the other if the filters were responsible? I am reluctant to mess with the filters as it a lot of work to implement in the first place. All the filters do is to MOVE a message to a local subfolder so I have them stored locally. Then I can back them up. You would be surprised how often I have had to refer back to a client email from over a decade ago! That is why they are all carefully filed. I am not sure where on the status bar I would see a message count. I do not see a way to do that in the status bar.

The status bar has an unread and total message count for the current account or folder. Do you not have a status bar?

Mine only has Unread. Perhaps there is something in the settings to cause both to show up.

Hi Local Folders - you mention that the filters move messages (not copy) to Local Folders. Note that I put that in capital letters. Are these folders truly in the Local folder structure? If they are - that move takes them off the server, and stores them locally only. If you have two computers each moving messages to their Local folder structure, each message can only be on one computer. It is no longer in the IMAP folder structure and can't be visible from the other computer. If this is the case please review how Local Folders works - it is a truly local offline storage structure, separate from the IMAP folder. Hope this helps, Agnes

If you have two computers each moving messages to their Local folder structure, each message can only be on one computer.

Couldn't have put it better.

Thanks Agnes - that explains it completely.

Therefore if I have it copy instead of move to local folders in the filter it should solve this issue as far as both computers having the same list of emails. Then I will have to figure out how to delete the files on the IMAP server after a while so they don't occur in two places.

Thanks very much. George

You may want only one of your two computers to have the filter turned on, so all the saved copies are in one place, not scattered across two. You can keep the structure of filters but just deactivate them on one. I would also consider having the filter move to a specific folder(s) in IMAP area and copy to the Local Folder area at the same time. Then the specific folder (IMAP) can be cleaned up by date range from time to time, knowing all content is safely stored. Glad to have solved the issue for you! Agnes