The process of exporting email from Outlook to Thunderbird on Windows is really easy. Exporting it from Thunderbird and importing in to Outlook is not hard either, just time consuming. Both ways can be done.

Outlook to Thunderbird
This is actually really easy. The first thing you need is all your email in Outlook. Then, when you setup Thunderbird it will ask you if you want to import your Outlook email. Say yes and it does all the work. No, Thunderbird doesn’t have an import function for the PST file, but it can import anything that’s in Outlook on the same machine. It’s as easy as that.