I've inherited a setup where the mail server is exchange 2010. For some reason, I'm not sure why there is 2 MX records setup. One being the exchange server which is the higher priority while the external (non-exchange) server is the secondary mx record. I don't believe this was done for redundancy reasons as the other mail server is not set to route mail back to the exchange server (it's just the webhosts email for their hosting) The client has been experiencing disappearing email, however after my investigations its not actually disappearing, but exchange is successfully receiving the mail and then passing it on to the external server. It isn't happening all the time, just with some email messages from some domains. My question: Is exchange passing the mail on because it can see the secondary MX record and is configured (somewhere) to send mail out? If so, how do I stop it? Is it as easy as just removing the second MX record pointing to the external mail server and exchange will stop passing mail on? I'm not exchange expert so I'm kinda stumped. Exchange MX tools are saying everything is setup and configured correctly from an external point of view.