See if this halps:
https://www.reddit.com/r/Thunderbird/comments/1hwzpjh/solved_the_current_operation_on_inbox_did_not/
Added new Outlook email account to Thunderbird > authenticated but not connected
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Dale Webb
0
Reputation points
Had to create a new Microsoft account. Tried to add associated email account to Thunderbird email client. Added account > TB went to get mail > Authorized but not connected or the current operation on 'Inbox' did not succeed. The mail server for ******@outlook.com responded: Command Error. 12. Thundbird evidently cannot connect to populate/subscribe IMAP folders.
Appears to be a server side error that I cannot overcome. Anyone that can help?
Outlook | Web | Outlook.com | Settings
3 answers
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Gérard Oomens 121.1K Reputation points Volunteer Moderator2026-03-30T20:26:06.3266667+00:00 -
Dale Webb 0 Reputation points
2026-03-30T21:28:20.2733333+00:00 I have flipped the switch in Outlook.com to allow IMAP to be used by others SEVERAL time. Each time I went back, it was flipped BACK to OFF. I saved it on the way out each time.
Went back ONE MORE TIME > was switched off > flipped it back on and saved. Outlook folders FINALLY populated. Microsoft is aggravating.My OLD Outlook email is locked in Microsoft Hell. Trying to log in only gives me options I cannot use or are unavailable to me. Same thing happened with my Microsoft account. That's why I had to create a NEW MS account. I'd REALLY like to log into the old account long enough to turn on FORWARDING to the NEW account. Any possible way I can do it?
TRIED to make AUTHENTICATOR work. Seems that's the ONLY WAY Microsoft will accept 'allow' to a prompt when I try to add an Outlook account to GMAIL on my phone. Authenticator proceeded to take over my MS account and make it impossible for me to log in. That's why I'm still stuck. Want NOTHING to do with Authenticator ever again.
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Gérard Oomens 121.1K Reputation points Volunteer Moderator
2026-03-30T21:43:02.44+00:00 Unfortunately, that procedure is fully automated.
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Dale Webb 0 Reputation points
2026-03-30T21:51:33.9766667+00:00 Now that Outlook folders are populated, tried to send 'change of email' message to about 60 people. Got message:
If I click: 'Enter new password,' a large window opens which displays nothing, goes away, and the app keeps trying to send. Recurs again after 30 seconds go by > ad infinitum.
Have REMOVED all stored passwords in Thunderbird. Anything else that might get through? -
Gérard Oomens 121.1K Reputation points Volunteer Moderator
2026-03-30T22:08:28.6333333+00:00 Perhaps you can ask in the Thunderbird community?
https://support.mozilla.org/en-US/products/thunderbird/support-forum
For a new Outlook/com account:
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Dale Webb 0 Reputation points
2026-03-30T22:27:46.79+00:00 One more thing (I hope). Why do microsoft server settings for personal outlook accounts seem to be a moving target. This is what copilot gave me, but SOMETIMES it says smtp.office365.com?
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Gérard Oomens 121.1K Reputation points Volunteer Moderator
2026-03-30T22:36:08.1066667+00:00 I see this:
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Dale Webb 0 Reputation points
2026-03-30T16:10:38.3933333+00:00 Could someone help me with this problem?
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Q&A Assist2026-03-30T00:34:57.93+00:00 AI generated content. This question contains an answer created with AI from Q&A Assist. Learn moreFor an Outlook.com account in Thunderbird that authenticates but cannot sync IMAP folders, the issue is typically that the account is still configured to use Basic authentication instead of Modern Authentication (OAuth2).
Use these steps in Thunderbird:
- Update the incoming (IMAP) authentication method
- Select ≡ (menu) > Account Settings.
- In the left pane, select Server Settings for the Outlook.com account.
- For Authentication method, change it from Normal password to OAuth2.
- Save the settings and let Thunderbird prompt for sign-in again; complete the Microsoft sign-in window.
- Update the outgoing (SMTP) authentication method
- Select ≡ (menu) > Account Settings.
- In the left pane, select Outgoing Server (SMTP).
- In the right pane, select the SMTP entry for the Outlook.com account and choose Edit….
- Set Authentication method to OAuth2 (instead of Normal password).
- Select OK to save.
- If problems persist, remove and re-add the account
- Remove the Outlook.com account from Thunderbird.
- Add it again as a new mail account and let Thunderbird auto-detect the settings. Modern Authentication will be used automatically; just sign in when prompted.
These steps switch the account to Modern Authentication, which Outlook.com now requires and which Thunderbird supports, allowing IMAP folders to populate and sync correctly.
References:
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Dale Webb 0 Reputation points
2026-03-30T02:16:41.3033333+00:00 I have done all those things. Nothing changed. This is a BIG problem for me as it is my PRIMARY email.
Sign in to comment - Update the incoming (IMAP) authentication method