Actually, this did not work. I can download a single email as a text or HTML file, but large numbers of emails can only be saved in ThunderBird format. What I need is a way to save 140,000 emails to a text format for legal archiving.
Yes, I did.
And I can download the emails from a single folder that way.
Unfortunately, I have hundreds of folders.
Well, no one said life would be easy.
It will take me a while, but I only have to do it once.