I have one exchange server and am using an external smtp server to deliver outbound mail. I recently had many DNS errors with aol.com particularly, and also noticed one odd error that stated there was an error resolving the senders domain, which would be my own domain. Basically my question is, what does an external smtp server need in order to properly deliver mail, both inbound and outbound. Currently my smtp server in the dmz uses my ISP's dns server to deliver mail, and my domain name is mcwe.com. thanks.
