Just to help, in case you have the following problem : transferring Outlook contacts (on one PC) to Thurnderbird (on another one).
Normally you can export Contacts from Outlook to a USB key for example, and then import them into TB. But for some reason, I couldn't do it, even though I tried all formats of export files, etc...
It actually is very easy with MPE : I downloaded the extension https://www.fjsoft.at/files/mpe-addin.xpi and installed it in Thunderbird, and voilà, it worked seamlessly.
(Oh, and I installed the Ligthning extension on TB to get the calendar /agenda functionalities. Same easy transfer of calendar data with MPE !)
MPE is a great and very flexible tool : bravo !
PS : I'm using Windows 7 on the "old" computer, and Windows 10 on the new one.