You're right, Microsoft will disable password based authentication for IMAP and POP soon as described i.e. in this post.

Now to your specific situation. Q: is this a personal or a work/education account? The personal ones do not work (neither China nor rest of the world) with OAuth2 at present, but work is underway to get this solved. For work/education accounts it works in principle, but probably not for China as the config for the partner.outlook.cn servers is missing in TB and that is why you cannot select OAuth2 I'll try to figure out the relevant data and raise a bug ticket to have this incorporated.

For now, all you can do is to use application passwords with Thunderbird: logon to your Microsoft account on the web and generate an App Password as described here. Please use the new app password as a "Normal Password" with IMAP and SMTP.

I would expect that there will be an automatic migration to OAuth2 once available in TB.

Thank you very much for your reply. We use a working account. After our own test, we regret to find that, as you said, Thunderbird only supports international accounts, not China. We asked Microsoft's customer service, according to them, the reason why the international version can be used is that Thunderbird is registered in Microsoft applications, but not in the domestic version of Microsoft applications, which leads to this result. Since the deadline for new authentication in China is 2023-3, we need to find a software that can support new authentication, in addition to outlook. I sincerely hope Thunderbird can adapt to China, so I don't need to replace other clients. After all, it's really easy to use and a great software. Looking forward to the update of Thunderbird, I believe that if Thunderbird can adapt to China as soon as possible, I am willing to recommend it to more people. Thank you again for your answer!

Perhaps try the OWL addon. It is not free

@JP. What is the bug that this work is being undertaken on?

I filed a bug to get outlook.cn on the radar: https://bugzilla.mozilla.org/show_bug.cgi?id=1780765

@Matt: There are (at least) three more bug reports related to M365, outlook.com, outlook.us: https://bugzilla.mozilla.org/show_bug.cgi?id=1685414 https://bugzilla.mozilla.org/show_bug.cgi?id=1699487 https://bugzilla.mozilla.org/show_bug.cgi?id=1780083

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