Funny thing about Microsoft, they still refuse to offer open standards access to contacts and calendars and are still trying to remove such access to email. They are still trying to enforce they proprietary connection protocols so Thunderbird has never supported the proprietary protocols instead focusing on the open standards. (CardDav and CalDav)

But there is an addon that offers to do the heavy lifting for you where proprietary protocols are concerned. https://addons.thunderbird.net/en-us/thunderbird/addon/tbsync/ and the Wiki for the addon https://github.com/jobisoft/TbSync/wiki

Thanks for your rapid response Matt. I downloaded "TbSynch" and "Provider for Exchange AcytivSynch". When I click on TbSynch:idle on the lower right corner, it responds "There are not yet any accounts defined". My email is defined and working well. I still want to use Tbird, but I need to know how to proceed. 1. Step by step to create profile (user account). 2. Need to know how to include my .PST file, for my historic emails saved locally on C:. I know that's a lot to ask, and I'm behind the curve, but I really need to know if I can get Outlook.exe (2021) features in Tbird, and that it will solve the MS Outlook denigration. Thanks again, Steve

I tried adding my account. TbSynch Credential request WILL NOT accept my email password. But now the lower right message says TbSynch:Synchronizing. Calendar still says "All calandars are currently disabled . . ." I have no idea what my Calendar name is. I think Microsoft has been successful in disabling Tbird. Steve

After giving up on Tbird I started screwing around with it. I discovered one must actually type in passwords or they are not accepted. Interesting. I was able to import my Calendar and Contacts. YEA! Now, all I need is access to my .PST file. Any help? Steve

Now, all I need is access to my .PST file. Any help? Steve

None. Thunderbird does not have any idea what a PST file is. It can import from a working, functional copy of outlook that is set as the systems default mail handler though. The import works through Thunderbird "asking" outlook for data and getting it, not through Thunderbird having any clue how Outlook stores that data.

Yes. Too bad. Import brought my Contacts and my Calendar. But I really needed .PST functionality. After "giving up" on it I got it customized nicely. Again, too bad. Thanks for your direct answers Matt. Steve

For pst import, see https://support.mozilla.org/en-US/questions/1394487

https://support.mozilla.org/en-US/questions/1397983