I have two email accounts. One is from Google (gmail.com), and the other from Microsoft (outlook.com). Two-factor authentication’s enabled on both accounts. When Microsoft announced they will end support for Windows Mail in 2024, I switched to using Thunderbird on Windows. I already use it on Solus Linux (my GNU/Linux distribution of choice), so the transition was uneventful for me.
A few weeks ago, Thunderbird started reporting that the connection with the Outlook email server has failed. The first thing I did was check that I could log into my Outlook email account on the web (in Firefox). I could. Next, I checked that the configuration in Thunderbird had not changed. It hadn’t. I went back to using Windows Mail until I could find a fix. It was able to access my Outlook email account successfully, so I knew the issue must be related either to something in the most recent Thunderbird release, or some change on the Outlook email server that Microsoft didn’t inform users about. Because I’ve had unrelated issues to deal with, and I can access both email accounts using Windows Mail, I’ve put off finding a solution until today. After reading several posts on the Internet about similar issues, I found a solution that works for me. I’m writing this on Windows 11, but the settings should be similar for GNU/Linux (I’ll know when I fix my Thunderbird settings on Solus Linux too).
If you have a Microsoft account that’s associated with your Outlook email account, you have two-factor authentication enabled for your Microsoft account, and you can’t access your Outlook email account in Thunderbird, this may help:
Before you start making any changes (there will be two), update your OS (including Thunderbird), then restart your system if necessary (new kernel, etc.).
In Thunderbird’s navigation pane (left – where your email account(s) and folders are listed), ALT+Click your Outlook email account and select Settings in the context (pop-up) menu.
This will open a new tab containing your Outlook email account settings. Near the bottom (lower-right), click the Edit SMTP server… button to open the SMTP server settings dialog.
In the Security Settings area, change the Authentication method setting from Normal password to OAuth2, using the drop-down list.
Click the OK button to close the dialog.
In the left pane of the Account Settings window (under your Outlook accounts email address), select Server Settings. The right pane now contains your incoming email server settings.
In the Security Settings area, change the Authentication method setting from Normal password to OAuth2 using the drop-down list.
Close the Account Settings tab and restart Thunderbird. After Thunderbird restarts, you should be required to authenticate with your Microsoft account, using your second factor device (for it’s my phone).
Note: After completing the two changes, restarting Thunderbird, and authenticating with my Microsoft account, I successfully sent myself a test message from my Gmail account to my Outlook account, so this solution resolved my issue. I followed these directions in Solus Linux, and everything works essentially the same.
UPDATE:
After regaining access to my Outlook email account on both Windows and GNU/Linux, I decided to compare its configuration with my Gmail account. When I originally set up Thunderbird, I let it configure both accounts automatically. On Gmail, the Authentication method was set to OAuth2, while on Outlook, it was set to Normal password. That’s because I had to set up an Application password for Thunderbird in my Microsoft account, and use it. Knowing this leads me to believe that my access issue was caused by some change Microsoft must have made to their outlook.com server’s configuration, or some change regarding Application passwords in general, and had nothing at all to do with Thunderbird. My issue could have been avoided if Microsoft had notified me that my Account passwords would stop working before they made the change. If you don’t use Thunderbird, but want to try it out, and you have a Passwordless Microsoft account (for Outlook), I suspect that Thunderbird will set it up using the OAuth2 setting, so you probably won’t experience this issue.
I hope this helps others,
Ernie