(In reply to Andrei Hajdukewycz [:sancus] from comment #14) > It also seems like SMTP Auth may simply be disabled with some types of accounts, [Microsoft states "Oauth 2.0 client credential flow with non-interactive sign in".](https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#smtp-protocol-exchange) > > If basic auth for SMTP only works for you(using user/password) I think that's what you should use for now, even if you're using oAuth for IMAP. This is completely nuts, but it seems to be what Microsoft wants in at least some cases... > > It's completely unclear to me why SMTP appears to work sometimes but not others, even when SMTP AUTH is enabled for a tenant. You're right, my bad. For my account SMTP OAuth does not work with TB 102.6.1 as well now, so it must be something on MS side not related to this bug.
Bug 1775077 Comment 16 Edit History
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(In reply to Andrei Hajdukewycz [:sancus] from comment #14) > It also seems like SMTP Auth may simply be disabled with some types of accounts, [Microsoft states "Oauth 2.0 client credential flow with non-interactive sign in".](https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#smtp-protocol-exchange) > > If basic auth for SMTP only works for you(using user/password) I think that's what you should use for now, even if you're using oAuth for IMAP. This is completely nuts, but it seems to be what Microsoft wants in at least some cases... > > It's completely unclear to me why SMTP appears to work sometimes but not others, even when SMTP AUTH is enabled for a tenant. You're right, my bad. For my account SMTP OAuth does not work with TB 102.6.1 as well now, so it must be something on MS side not related to bug 1810760.