If I change Exchange from sending mail directly to using a smart host (our ISP), does that have an impact on the PTR record for Reverse DNS checks ? Would it need to be changed ? Presently, we have a PTR record to resolves to mail.mydomain.com, which is our public ip address where traffic on port 25 is forwarded to our SBS2003 Exchange server.
I'm trying to understand how a receiving server does it's Reverse DNS check. Is it done on the ip/name of the host server (our ISP) that would send the email for us, or does it do it based on the sender's domain name.