Setting up a CNAME record for any of the domain names or subdomains you have in the hosting account will allow you to redirect it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX etc, and will take the records of the domain name it's being redirected to. In this light, you can't set up a CNAME record to direct your domain name to a third-party provider and maintain a working email service with the first provider. It is also essential to know that a CNAME record is always a string of words rather than a number as it's commonly wrongly identified as the A record of the domain name being forwarded. One of the primary uses of a CNAME record is to direct a domain name you own through one company to the servers of some other company when you have set up an Internet site with the latter. That way, the site will appear under your own domain, not under some subdomain provided by the third-party provider.