How would you move a bunch of Thunderbird mailboxes over to Mac Mail?

[Aeschines]

I tried to do an Import, but at the very least it seems extremely complicated. There is no "Thunderbird" option under Mail Import, though there is one for Netscape/Mozilla.

If you suggest Import, please provide detailed instructions. Otherwise, other suggestions would also be appreciated.

Thank ye!

[Bag of Mostly Water]

I would try to easy way -- drag a folder in Thunderbird to the desktop. This should create a .mbox file. Then drag the .mbox file into mail. Make sure you drop the file where you want it. Repeat for each folder you have in Thunderbird -- you should be able to select as many folders as you like at the same time.

This worked with every email client I've tried except Outlook.

[Aeschines]

I tried that. It just doesn't seem to work.

[Bag of Mostly Water]

See this thread (http://discussions.apple.com/thread.jspa?messageID=717490򯊲) on the Apple discussion boards. Here is the key recommendation:
since Thunderbird is a Mozilla-based client, you would select "Mozilla" in Mail's import dialog. However, since Mail's import function from TB has some shortcomings (it doesn't deal with Windows and older Mac files, you will lose all your message status flags, ...) you might want to take a look at Eudora Mailbox Cleaner as an alternative (and imports messages from TB to Mail as well):

http://homepage.mac.com/aamann/