An alternate way to do this instead of running clean-up scripts, if you have access to Entourage, can be found on a posting from petterpp on Jun 23 2005, 18:42 at: http://www.neowin.net/forum/lofiversion/index.php/t317094.html.

Here is what you need to make it work - it did for me, at least. (I actually created a blank mailbox folder in Entourage to drop the Thuderbird files in).

"I have had the same problem as you until today! I found a way that works good.

1. Install Entourage
2. Find your mailfolders (found in Library/thunderbird/profiles/your account/mail/local folders)
3. There are three versions of your folders (Inbox.msf, Inbox.sbd, inbox)
4. Copy the one without extention to the desktop (or wherever you want)
5. Add the extention .mbox to your folders
6. Open Entourage and drag the folders to the main folder (Folders on my computer)
7. Open Mail and go: File/Import and select Entourage.
8. Done!

Hope this will help all frustrated minds out there.

/Petter"