I have two PTR records already setup with my ISPs for rDNS. I also have two IP blocks from ARin.net. My email is coming/going on this IP 1xx.2xx.1x1.xxx from Arin. This IP is nat'd back to the spam filtering appliance which in turns forwards it to the exchange server.
Example: When i email someone that checks for rDNS the IP they see is 1xx.2xx.1x1.xxx (Not the ISP IP address). how do i assign a hostname to this IP?