Hi Balamurugan-S,
For your question, do you complete the steps in below link to configure server-to-server authentication between Exchange 2013 and SharePoint 2013?
https://technet.microsoft.com/en-us/library/jj655399.aspx
If this issue persists, please run Get-PartnerApplication in the Shell to retrieve the configuration. Also run the Test-OAuthConnectivity to test OAuth connectivity with a partner application for a user.
https://technet.microsoft.com/en-us/library/jj218721(v=exchg.160).aspx
Best Regards,
Lisa Chen
TechNet Community Support
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