DNS server problem

Hi I'm in a bit of a bind with my DNS server. Currently its returning the wrong information for a few addresses like yahoo and aol. I found this out because we were having problems emailing to those domains and they kept bouncing. When we switched the DNS gateway to another server the emails went out and everything worked fine. From the best I've been able to determine its somehow gotten it listed that the name server is the mail server which is why we cannot email those domains. So my question is this how do you get the DNS server to request this information from those domains again? Is it something you can go in and modify a file to correct?

AOL is checking the source with a reverse DNS.

You can go to http://www.dnsstuff.com/ and see what happens when you enter your mail IP in the "Reverse DNS lookup" edit box.

If you are using Exchange Server 2003, you can follow the instructions at http://sbsfr.mvps.org/docexch/relais/ (it is in French, but the screenshots are helping a lot, and you can translate the page with translating tools).

You may find many other articles on the subject with Google.