I currently have a Trend Micro SPAM server and one Exchange 2007 server. Our MX record points to our Spam server (mail.abc.com) for all inbound mail.
Our Exchange server sends mail directly out to the internet without going through the Spam server.
My question is given this configuration.... for receiving email servers that perform reverse lookups like AOL, Comcast, etc. I know I need to have a PTR record in place. Does that PTR record have to point to my MX record (Spam Server) or does it need to point to the Exchange server (The outbound SMTP server).