It seems that thunderbird-102.7.1-1.el8 (at least on CentOS Stream) broke OAuth authentication with outlook.office365.com. Downgrading to 102.4.0-1.el8 resolved the issue. Error console reports: XHR POST https://login.microsoftonline.com/common/oauth2/v2.0/token [HTTP/1.1 400 Bad Request 293ms] Is anyone else seeing this? -- Orion Poplawski he/him/his - surely the least important thing about me IT Systems Manager 720-772-5637 NWRA, Boulder/CoRA Office FAX: 303-415-9702 3380 Mitchell Lane orion at nwra.com Boulder, CO 80301 https://www.nwra.com/