if you have been around a while you are probably familiar enough with ports and servers to use davmail. I blogged about it back in 2011 when I had an exchange server and it did the job for me. https://thunderbirdtweaks.blogspot.com/2011/11/thunderbird-and-exchange-owa.html http://davmail.sourceforge.net/index.html Then there is the exquilla add-on, but it's days are numbered. https://addons.thunderbird.net/en-US/thunderbird/addon/exquilla-exchange-web-services/?src=search Exquilla replacement? https://addons.thunderbird.net/en-US/thunderbird/addon/owl-for-exchange/?src=search Calendar https://addons.thunderbird.net/en-US/thunderbird/addon/provider-for-microsoft-exchang/?src=search Contacts tasks and Calendar https://addons.thunderbird.net/en-US/thunderbird/addon/tbsync/?src=search I have not had an exchange server for some years now, but those are the add-ons that are available, but as I said I used davmail because it "just worked" once configured and had no Thunderbird dependencies, a new version did not break an add-on.

Thanks! I did a little google but managed to not find those options at first glance. My IT folks tell me to give up as two-factor is going to break everything but Outlook when they turn that on in a few weeks...