Hi @engin_arlak
Thanks for your response, appreciate it.
Fortunately, able to solve the issue 
I just compared today whats the difference in payload data sent from postman vs our IS, able to find that there will be a hidden request header ‘Host’ will be sent which is nothing but the hostname from endpoint url.
The endpoint url we are calling had a Camel case and postman was setting the ‘Host’ with all small cases in the hostname, so we tried same by calling the hostname with all small cases in the endpoint url and it workedddd.
Regards,
Niranth