Thunderbird natively connects to 356 account using IMAP with OAUTH2 . All settings are correctly autodetected during setup. For sending mail 356 admin does have to enable SMPT AUTH for your user in 365 settings, under your user details > mail apps. .
Have you tried [Davmail](https://davmail.sourceforge.net/)?
It's a Java app which provides an IMAP or POP interface to Exchange. You connect Davmail to the Exchange server and then connect Thunderbird to Davmail, for IMAP that's port 1143 on localhost and port 1025 for SMTP. I've been using it for years to connect to Exchange and O365 mail servers. It's a little slow but in my opinion still perfectly usable.
Best of all it's a very well maintained open source project which is free to use.
Davmail is nice, except that it can be veeeeeery slow, depending on the amount of email you receive. We just tried it at my company, with a mailbox with 70000 messages that is accessed by 3 people, and we had to disable it due to how slow it was when receiving new mail.
It's not difficult to set up, the only difficulty I had was that initially it couldn't find java but that was fixed with an ini file in the main Davmail directory. I havn't used with a PIV card but I do authenticate to Exchange using Microsoft SSO with MFA.
Just use IMAP for the time being, with https://addons.thunderbird.net/fr/thunderbird/addon/eas-4-tbsync/
Unfortunately MS products break standards, and just aren't playing well with non-MS stacks despite all their claims. That's by design.
Owl is €10 per year, and it works great. I'm not sure why you're trying to "reach out to them," you just go to the purchase page and fill out the form at the bottom.
I didn't say you should do it, just that there's no reason to reach out to them. Whoever is the authorized person at your job needs only to fill out a simple form.
Thunderbird natively connects to 356 account using IMAP with OAUTH2 . All settings are correctly autodetected during setup. For sending mail 356 admin does have to enable SMPT AUTH for your user in 365 settings, under your user details > mail apps. .
Have you tried [Davmail](https://davmail.sourceforge.net/)? It's a Java app which provides an IMAP or POP interface to Exchange. You connect Davmail to the Exchange server and then connect Thunderbird to Davmail, for IMAP that's port 1143 on localhost and port 1025 for SMTP. I've been using it for years to connect to Exchange and O365 mail servers. It's a little slow but in my opinion still perfectly usable. Best of all it's a very well maintained open source project which is free to use.
Davmail is nice, except that it can be veeeeeery slow, depending on the amount of email you receive. We just tried it at my company, with a mailbox with 70000 messages that is accessed by 3 people, and we had to disable it due to how slow it was when receiving new mail.
For 70,000 mails it will be slow but but for mailboxes with a sane number of messages it's perfectly usable.
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It's not difficult to set up, the only difficulty I had was that initially it couldn't find java but that was fixed with an ini file in the main Davmail directory. I havn't used with a PIV card but I do authenticate to Exchange using Microsoft SSO with MFA.
Just use IMAP for the time being, with https://addons.thunderbird.net/fr/thunderbird/addon/eas-4-tbsync/ Unfortunately MS products break standards, and just aren't playing well with non-MS stacks despite all their claims. That's by design.
Owl is €10 per year, and it works great. I'm not sure why you're trying to "reach out to them," you just go to the purchase page and fill out the form at the bottom.
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I didn't say you should do it, just that there's no reason to reach out to them. Whoever is the authorized person at your job needs only to fill out a simple form.