UNIX for Dummies Questions & Answers

Hi guys

We have a client that gets NDR mails when sending emails to the domain "recipient.com"

My client's domain is "client.com"

My Client setup:

Server 2003 Domain
Front end Back end Exchange 2003 Standard SP2
1 Linux Firewall/Router

The NDR contains:

Code:

The following recipient(s) cannot be reached:

      'user@recipient' on 1/22/2010 12:07 PM

            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

            <exchange_primary.client.com #5.5.0 smtp;550 No RDNS entry for 192.168.0.xxx (IP of the Firewall)>

Now I know this error is caused by the fact that we do not have a RDNS entry for the domain/exchange/firewall.

I would like to know where this RDNS entry must be made. The receiving exchange server tries to do a RDNS lookup on the FQDN of the primary exchange server, but this resolves to the Linux Firewall's external IP address.

Where must I make the change then?

I did not set up the environment so not 100% sure.

Thanks