Creating a CNAME record for any one of the domain names or subdomains that you've got within a hosting account will allow you to redirect it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX and so forth, and will take the records of the domain name it is being pointed to. In this light, you cannot set up a CNAME record to forward your domain name to a third-party provider and maintain a functional email service with the first hosting company. It's also important to note that a CNAME record is always a string of words and not a number as it's regularly wrongly identified as the A record of the domain being forwarded. One of the primary uses of a CNAME record is to direct a domain address you own through one company to the servers of another company when you have set up a site with the latter. That way, the Internet site will appear under your own domain name, not under some subdomain provided by the third-party company.