According to this page you can export mail from Outlook 2003 as a .pst file and then presumably import it as a .pst file to Outlook 2007: https://support.microsoft.com/en-gb/kb/287070 You can then import from Outlook 2007 to an earlier version of Thunderbird: https://support.mozilla.org/en-US/questions/1073445 I'm not clear from your post if you can't run Outlook 2003 on your old machine. Even if you can't, this page rather implies that it stores the mail as a .pst file anyway, so maybe you can just copy it? https://www.howto-outlook.com/howto/backupandrestore.htm I hope this is some help. Personally I steer well clear of Microsoft products so I don't have personal knowledge of this process, maybe someone else will post further advice for you.

Outlook 2003 does work on my machine. I do not have Outlook 2007. After trying many things and being on the phone over 2 hr with my ISP I concluded that the best thing to do was to open another gmail account, Use Outlook 2003 to run it, transfer file by file to gmail IMAP, then on the new machine to put the data in local folders in a new version of Tbird. This is working. In another few hours I should be done. Thanks for the information, but I was into the gmail process by the time I saw it. I was trying to do it clean, not file by file, or group of emails by group.