Dear Sir,
This is an issue of rDNS management in your server. I can assure you that, please ask you server admin to add rDNS record with your name-server (ns1 / ns2).
I wish this will be solved by your server admin once rDNS added properly. This will take upto 72 hrs to reflect globally. And also hope, after this solution, You will pay me for this useful suggestion.
Thanks
-Rudraraj