EMAIL oAUth Authentication issue

[#1]

Hi Team,

We are working on connecting from SAP Cloud Integration to a mail account in Outlook 365 via OAuth2 with Authorization Code grant type, using the protocol SMTP for sending e-mails .

Followed this blog Cloud Integration - Connect to Microsoft 365 Mail ... - SAP Community and completed the configuration also developed Generic Iflow for sending emails .But while we are testing ending up with error as Authorization unsuccessful 

Please find the detailed error logs in CPI

“javax.mail.AuthenticationFailedException: 535 5.7.3 Authentication unsuccessful”.   Kindly advise on how to resolve this issue and what this error actually means.