Reading that same mozillazine topic, you might be able to create a POP account, then change it to movemail by changing the preference (right-click in Config. editor, Modify) mail.server.server#.type from pop3 to movemail, and adding two preferences, mail.root.movemail, whose value depends on your folder setup, and mail.root.movemail-rel, which appears to have the value [ProfD]Mail. New preferences can be added to Config. editor (in Preferences/Advanced/General) by right-clicking in the editor, New, (in this case) String.

You may have already tried all this, and I admit it's something I've never tested.

Hello, @sfhowes:

It worked! That is, by reading your message, then the mozillazine topic, then puzzling my way through creation of a POP3 account that doesn't exist, then puzzling my way through the configuration editor, then quitting and restarting Thunderbird, I was able to set up a Thunderbird account which did in fact read the messages in local system's movemail queue.

The next question is, what to do with these messages? I found that I could drag the messages from the inbox of this movemail account into the archives folders which I used for my other mail. I guess Thunderbird takes care of removing the message from the movemail queue and adding it to the archive folder.

A final question is, what happens to new messages which arrive to the movemail queue? I guess I can provoke the system to send some mail there, and see what happens. And, maybe a better solution is to configure sendmail on my local system, so that it can deliver mail on to my main email address, instead of letting them accumulate in the movemail queue. But that will be beyond the scope of Thunderbird.

I've no experience with movemail, so I can't say what happens for new messages. Maybe you can create a filter that automatically moves or copies them to a subfolder of Local Folders.