Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Users might experience few discrepancies in Search results. We are working on this on our side. We apologize for the inconvenience it may have caused.
New Member

MX record Reverse DNS lookup and NAT outgoing different IPs -- bounces mail

I have a PIX 520 that NATs all outgoing activity to a single public IP address. Our MX record is not the same public IP; mail services that do reverse DNS lookup to protect from spoofs and spam dump our do I configure the PIX so mail goes out with the appropriate IP address?

New Member

Re: MX record Reverse DNS lookup and NAT outgoing different IPs

I guess I don’t understand what you are saying. If your SP is hosting your SMTP, your inside hosts hand off the mail to that host (which in turn should be the same as your MX record.) When that server tries to send the mail to the correct address, IDENT should be allowed to that server to be sure the other mailservers can verify identity. If you host your own SMTP server behind your firewall, the MX record should point at the static translation setup in the PIX. Now simply open an additional conduit for IDENT and mail should work fine.

CreatePlease to create content