Reverse DNS is for if you are sending mail not receiving it. Aol and Msn and quite a few other companies require you to have reverse DNS setup.

Just so I have everything straight here. There are two servers involved and your trying to receive e-mail from the php web based form hosted off server1 and have it deliver the e-mail to server 2. The mail is not arriving or being rejected from server2 your newly leased server. Is this correct?



This is more than likely not something you can fix in cpanel. You will more than likely need to solve the problem through ssh. Can you provide the headers from the email that is being rejected? So I have 3 ideas as to why you are not receiving mail, but the headers on the returned email can help narrow it down.
What os is the server running? Is there a firewall?