Are you using Office 365 email with a private (custom) domain, or are you using a shared public domain such us "outlook.com", "hotmail.com"?. This is the part of your email address that comes after the @ character. Office 365 still doesn't work with OAuth2 when using a public shared domain (MS refers to these as "personal" accounts), at least on my end using Thunderbird 102.7.1. What works for me, is to use '''Normal Password''' authentication (which is what Thunderbird defaults to anyway), and an app password generated via my Microsoft Account's Security settings page. See https://support.microsoft.com/en-us/account-billing/using-app-passwords-with-apps-that-don-t-support-two-step-verification-5896ed9b-4263-e681-128a-a6f2979a7944