I have a client with a .pst file that is more than bursting at the seams. His OS is Windows 7 so I can install Live Mail, but that's only good until Windows 7 goes away. So I've opted for Thunderbird. But I'm not finding good information about importing his email.
I guess another possibility is to use Live Mail for now and see how it converts with the mail program in Windows 10. Has anyone made that transition?