Hello @DhananjaiSenthilkuma
That endpoint doesn’t return user emails, it returns user email ADDRESSES.
Also, that endpoint is not available to general OAuth 2.0 connections, only Connect apps, and they require Atlassian to approve that app, as per the endpoint documentation where it says:
Returns a user’s email address. This API is only available to apps approved by Atlassian, according to these guidelines
Scopes
CONNECT app scope required:
ACCESS_EMAIL_ADDRESSES