The Microsoft email included a link with detailed instructions for Thunderbird: https://support.microsoft.com/en-us/office/modern-authentication-methods-now-needed-to-continue-syncing-outlook-email-in-non-microsoft-email-apps-c5d65390-9676-4763-b41f-d7986499a90d

The MS instructions do not work

I was able to switch the Authentication Method to OAuth2 under "Server Settings",

but I was *not* given that option when I tried to do the same thing for "Outgoing Server (SMTP) Settings". I was only given the following options: • No authentication • Normal password (which is what it has been set to) • Encrypted password • Kerberos/GSSAPI • NTLM

Now Outlook is not operating from within Thunderbird.

There must be a huge number of uses this is affecting. Please help.

did you change smtp server to smtp.office365.com?

Thank you for the prompt reply. No I did not. I didn't see any instructions to do so.

Once it failed to access my email I desperately tried option 2 - delete the account in Thunderbird and Add it in again.

• • • That appears to be working although it is going to take a while to download and index everything.

Thank you. I hope others have luck accessing their email

That was the smtp server in the graphic instructions, so I felt it worth a try, since the instructions for incoming server were different. SO, did you try it or not? Knowing that can be useful.

No. I did not.

The second step in the instructions were not doable.

I was *not* given that option when I tried to do the same thing for "Outgoing Server (SMTP) Settings". There was no option to select OAuth2 as directed.

No, you did not what? I don't understand.

Your question: did you change smtp server to smtp.office365.com?

My answer: No. I did not.

well, that was the server shown in the graphic. I believe it's worth trying the examples before saying the instructions don't work.