Outlook 2016 doesn't accept password or app password

Another authentication error just now. 9Folders email client. Exchange Activesync.

Thank you for your help bringing attention to this matter, Pierre. You may not have noticed, but Gabriel Bratton, another Microsoft Agent on this Answers forum, has been kindly active here with us working as a liaison with the Outlook Team, and posting updates periodically on your thread. That said, I agree with you that the Support incident report should not be marked RESOLVED.

Nobody replied to you in this thread, you are just posting in the wrong one.

I don't mean to disrespect or downplay other issue, but in regard if that is true or not, is a complete new topic that can be discussed into another thread by whom my be interested.

Please let's try to focus on this issue and and not slide the thread.

Thanks

Can Gabriel or someone from Microsoft explain why the burden of figuring out these new protocols is the users' responsibility? It's your platform that doesn't provide non-365 accounts a valid, stable connection. I use Thunderbird 102 with an exchange connection and an app password. It was reliable and stable for countless years until four weeks ago, when it stopped working altogether. With the prematurely announced recent "fixes," it now works intermittently but with no logic/reason as to when or why. I pay for a Microsoft 365 Personal account for a legacy Hotmail address. I (and others like me) would very much appreciate some support.