There is an addon that i think will handle the address book. It is at https://services.addons.thunderbird.net/en-us/thunderbird/addon/outlook-address-book-enabler/ There is no Thunderbird tool to convert PST files to mbox, but there are several third-party tools that do that. I did locate this URL (developed by another company so I can't comment on the details) but it does explain several options and may be helpful to you: https://www.syscurve.com/blog/how-to-import-outlook-to-thunderbird.html