Seems to require changing the Authentication Method to OAuth2. Microsoft that will generate a popup that you fill in when you reload TB and it appears to work after that.

Does anyone have an insight into why this has changed?

Sorry, where do I need to change these settings, in Thunderbird or Office365?

I have exactly the same problem as you, a few hours ago Thunderbird logged in normally to Office. Not any longer. And the problem persists on both my laptops. Logging into Office from the website works normally, and Apple Mail logs in normally on all my devices so the I guess the issue is with Thunderbird.

Nevermind, I found it (Tools-Account settings-Server settings). But when I changed the authentication method to OAuth2, restart TB and try to get new messages, it says: "Error with account (my e-mail)

The server does not support the selected authentication method. Please change the 'Authentication method' in the 'Account Settings | Server settings'."

Changed it back to "Normal password", and the original problem is back.

So do a lot of people...

In Thunderbird go to the Tools menu (if not showing at the top press the Alt button).

You then need to alter how the e-mail is authenticated for both the outgoing and incoming e-mails.

• Tools/Account Settings
• e-mail account/Server Settings/(Security Settings)/Authentication method = OAuth2
• Outgoing Server (SMTP)/Edit SMTP Outs/Authentication method = OAuth2

Then press OK

Exit Thunderbird, reload, a Microsoft screen should appear and enter your password.

That should be it.

Best wishes.

Works on my spare laptop, so probably it should work on my normal one as well. Thanks a lot!

"...probably it should work..."

On my other laptop I made the very same adjustments, in the Server settings and Outgoing server, closed and restarted Thunderbird.

Instead of the Microsoft password popup I get the same "The server does not support the selected authentication method. Please change the 'Authentication method' in the 'Account Settings | Server settings'." Both laptops (Macbooks) run the same version of TB 91.11.0 (64-bit) and try to log into the same four Microsoft 365 mailboxes so how can this even be possible.

[Spoiler Alert: Mild Rant Mode = On]

Someone on the Thunderbird programming team needs to look at this. This has been a perennial issue. If nothing else Thunderbird should diagnose the base problem and give the user a better explanation and steer as to what needs to be done.

Having run a software firm that produced e-mail clients for a decade in the early days of the Internet this is more surprisingly easy to do than you might assume. It's more a question of the development will. And the amount of user frustration and unnecessary support time wasted doesn't bear thinking about.

Still having this discussion in 2022 rather than 1992 is ridiculous.

The problem is that if it continued I'd have had to switch to Outlook, which again isn't a perfect offering, but e-mail is so critical you just need a product that works.

The other side of the issue is that Thunderbird only 'knocks on the door' of email accounts and the account must accept the credentials as presented. There have been many such incidents posted here (most about Gmail), but the root cause is not Thunderbird; it is the email hosts that change their requirements and do not notify their customers. And also the customers who look solely to Thunderbird, as the messenger, to be responsible. When people find that their login works one day and not the next, the first place to check should be with the email host. In helping others, I routinely scan the email host's website to find the setup requirements and then notify the user with the info that was available to them. So, please hold off on your criticism of Thunderbird programmers, as it is not they who cause this confusion. Thank you.

No it's not a criticism: it's an observation, based on experience. In the very early days of e-mail when most users didn't have a clue how things worked the propensity for software to not install so that it was workable or appeared to malfunction was infuriatingly high. One year we devoted around 25% of programming effort into getting the software to self-rectify or explain issues and the "user experience" and the "support sanity" was transformed (75% improvement).

Today, with a few key players dominating the e-mail supply: Gmail, Apple, Microsoft the ability to explain, statistically, most of these issues are surmountable or at least improvable.

It's not a criticism of programmers - they're wonderful. It's more a criticism of schedulers, people like me of old, who prioritise their workloads.

This is a persistent issue. Outlook has this habit as well. But the more we can do to help the users the better.

E-mail is probably the most important, critical and sensitive app to all users.

And keep up the great work.

It's something happening to a load of people who use various servers. The owners of the servers have been changing what they accept for Authentication Method and also in some cases forcing people to use app generated passwords where Oauth is not used; in the case of Xfinity they created a new option in webmail which had to be selected. But the problem is the lack of communication given to their customers - eg : you. This ends up with people struggling to get access to emails when using third party email clients. Naturally, it is blamed on whatever email client they use because let's face it, the settings are wrong and the server says 'no'. Once the users knows what to do, it is often it is easy to create everything new on an email client that did not have the account previously. In Thunderbird, if account was previously set up, there are many settings that need adjusting because various files need to get rewritten.

I agree it sounds like this should be easy and it is, but if you miss out one process, it can be a pain getting it all in synch again. I've come across people missing out parts of the process, trying all sorts of things and ending up creating a real mess of files - not funny.

There are Help Articles that have been edited, but they are not necessarilly all passed the review stage before publicising. All Articles are mainly written and/or edited by volunteers. Sadly this means they are always in a catch up situation and not everyone locates those Help Articles, so they attempt to fix, get frustrated and ask for Help in the forum. So, the volunteers who help in this forum have come across many variants of what might seem like the same problem, but in reality, tracking down which bit is failing can sometimes be frustrating to say the least.

Check the following to see if this sorts out the problem. Having changed both incoming and smtp Authentication Methods to OAuth.

Did you delete the stored passwords and make sure Thunderbird can accept cookies. Menu app icon > Preferences > Privacy & Security WEb Content: Select 'Accept cookies from sites'

Passwords section Click on 'Saved Passwords' click on 'Show Passwords' select relevant imap:// and smtp:// and Oauth lines for the account and click on 'Remove'.

Then exit Thunderbird - wait a few moments for background processes to complete. Start thunderbird and at prompt enter the password to allow Thunderbird access.

Did the above get things working again?