I'm having trouble understanding MX records. We have three domain names hosted by WhoIs (first mistake I think). Our DNS information points to the DNS servers at Network Solutions since that's where our website and email is hosted.
We're going to be switching to Arvixe hosting in the next week or two and also switching to using Exchange Server on our own server in-house to host email. Where will I edit the MX record to point to our static IP at our office? Is this some that is controlled by the domain name registrar or the hosting provider?