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PSA: We're aware of an issue affecting #Thunderbird users using #IMAP to connect to certain #Microsoft account servers (for example: outlook.office365.com).

These users are receiving an error message that says "User is authenticated but not connected."

We believe this is caused by Microsoft running certain services with broken #IPv6 functionality.

WORKAROUND: Disable IPv6 networking in Thunderbird's advanced config.

MORE INFO: https://answers.microsoft.com/en-us/outlook_com/forum/all/thunderbird-imap-responded-user-is-authenticated/062a82f6-e678-4462-88b7-dd6cc318386f?page=1
This entry was edited (1 year ago)

Ondřej Caletka reshared this.

in reply to Thunderbird: Free Your Inbox

it could also be that Basic Authentication (IMAP and POP) is being turned off for everyone this week!

Modern Authentication is required which doesn't work natively on TB
in reply to Thunderbird: Free Your Inbox

That would kill the connection to my own server that's IPv6 only inside my home network 🫣
Good thing I don't have a MS Server I need to connect to badly 😅
in reply to Thunderbird: Free Your Inbox

Microsoft provide no support except "we receive your message". Do people pay for that?