I am currently using nat translations to nat inbound smtp.domain.com traffic to a specific IP address and another public IP address for outbound email messages. My question is, where does the PTR get pointed to? Should it point to the inbound public ip or the outbound public ip address? Right now we have our smtp.domain.com MX record pointed to the Public IP where mail comes in and we also have the PTR associated with that same public ip. Is there a problem with that?
I was thinking about placing the PTR record on both the inbound and outbound Public IP addresses, would that cause a problem?