I cannot answer all your issues, but I'll share a bit. First, the beta version is unstable. I encourage setting her email account with the latest stable version. The beta is not downward-compatible. Second, the Outlook account must be on the PC and be the default email client for TB's import to function. As far as the conversion, there are many websites with suggested steps on the process. Good luck.

David's reply: "As far as the conversion, there are many websites with suggested steps on the process. Good luck."

So that is the help you offer? Go some place else? Really?

I understand that the developers are volunteers, but I find it a bit baffling that getting the import function to work can be so hard. I have a standard Outlook install that I formerly used. I have a standard Thunderbird install that I am using now. I am running Windows 10. How can the profile not be found?

Good luck in getting the import to work.

I gave you good advice: do not use the beta. and I also explained the Outlook requirement to save you attempting to resolve it. As far as converting your .PST file, that is not our strength, although some here know more of that than others. "Outlook' applies to more than one email setup; if Thunderbird cannot find the Outlook profile, that is a sign that your setup is not supported. And, since you didn't appear to follow my other suggestion, I offer you this URL to assist you: https://www.syscurve.com/blog/import-pst-to-thunderbird.html

On your comment, developers are paid, even though fewer than 1% of the tens of thousands of users donate to help further the product.

@larry merk

I tried recently with success to import a pst file to Thunderbird, had good luck with using pffexport (sudo apt install pff-tools on a Debian-like Linux distro) to convert it to a Mbox formatted file, then using the Thunderbird add-on ImportExportNG to import the Mbox formatted file. I understand that under Windows there is floating around advice about Mapi, it should of course require to have a running Outlook to work, but frankly I don't trust it much and anyway I don't run Windows on my computers so it was not an option.

The way I used is 100% open source, there are paid solutions that may be all in one and fully automatic without more or less manual steps, that's I think was implied in the first reply, but it's not possible to advise for that on a forum for open source software.