Announcing OAuth 2.0 support for IMAP and SMTP AUTH protocols in Exchange Online

Abheek_Das:  

SMTP.Send with Outlook REST V2.0 API works fine.

Same client using Graph V1.0, the only change being the ‘scopes’ URIs, gives a ‘535 5.7.3 Authentication unsuccessful’.

However, AAD’s Sign-in logs (‘User sign-ins - non-interactive’) for the app show ‘Success’.

Unless Graph SMTP.Send uses a different server URI than the published https://smtp.office365.com, this should be impossible.

I gather from Stackoverflow, learn.microsoft.com and similar forums that others have run into the same issue and are unable to move to Graph - with big problems (and no workaround) looming when you decommission the Outlook REST V2.0 API  in November '22

[For reference, we use V2 Authorization and Token endpoints, and scopes URIs of https://outlook.office.com and (the default)  https://graph.microsoft.com respectively, with the same scope SMTP.Send]