Today, we’re excited to announce the availability of OAuth 2.0 authentication via client credentials grant flow for the POP and IMAP protocols for accessing Exchange Online mailboxes.
Applications ...
Updated Jun 30, 2022
Version 2.0
Blog Post
1 MIN READ
Announcing OAuth 2.0 Client Credentials Flow support for POP and IMAP protocols in Exchange Online
Just to let everyone know, after I was able to obtain the OAUTH bearer token, I then faced an Authentication Failed error while trying to use that token to send SMTP emails using client credentials flow.
It turns out that my Azure server had not been fully configured with all the permissions needed to send the emails.
The last steps described here-> https://learn.microsoft.com/en-us/exchange/client-developer/legacy-protocols/how-to-authenticate-an-imap-pop-smtp-application-by-using-oauth#register-service-principals-in-exchange to create the service principal and give it permissions to the target mailbox had not been done.
Once this was completed, I was able to send SMTP emails through javamail successfully.