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Thunderbird OAuth2 does not work for Shared Mailboxes on O365

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Espresso366
Espresso366

Microsoft is enhancing security and disabling Username/Password in favor of OAuth2 authentication. While this works for the primary account, Shared Mailbox accounts will not connect with OAuth2. There is a temporary solution to re-enable the legacy authentication, but this too will be disabled in September, 2022 (according to MS Support).

Reference Pages: Setting up Shared Mailbox in Thunderbird: https://www.en.its.aau.dk/instructions/Mail/shared-mailbox-thunderbird/

MS OAuth2 Guide: https://docs.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#sasl-xoauth2-authentication-for-shared-mailboxes-in-office-365

Microsoft is enhancing security and disabling Username/Password in favor of OAuth2 authentication. While this works for the primary account, Shared Mailbox accounts will not connect with OAuth2. There is a temporary solution to re-enable the legacy authentication, but this too will be disabled in September, 2022 (according to MS Support). Reference Pages: Setting up Shared Mailbox in Thunderbird: https://www.en.its.aau.dk/instructions/Mail/shared-mailbox-thunderbird/ MS OAuth2 Guide: https://docs.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#sasl-xoauth2-authentication-for-shared-mailboxes-in-office-365