It has gone downhill... but still much better than the "New Outlook". Any other recommendations?

Considering this as the Thunderbird Import tool only sees the "new Outlook" data, despite my uninstalling it. It doesn't see the "classic Outlook" data even though it is there. I may have to export a .pst file from Classic Outlook and find a way to import to Thunderbird.

I have a client who got accidentally upgraded to "the New Outlook" in Windows. But it didn't bring over the saved folders in the Classic Outlook. What a pain. This looks interesting: https://github.com/james-hu/pst2tb