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

Anthony_Gentile_FUB 

Hi Anthony

Thanks you for your comment. New organisations onboarding to Exchange Online now have SMTP AUTH disabled by default for their tenants. This was taken with security in mind, with the understanding that there may be friction. Given that this is a protocol-based setting, OAuth will not work either unless the protocol is enabled for the mailbox.

As part of onboarding to use your app, they will need to either turn on the protocol for the mailbox or for their entire tenant. You can direct them to the documentation explaining how to do this here:

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission