Creating a CNAME record for any of the domains or subdomains you have within a hosting account will enable you to redirect it to a different domain/subdomain. The forwarded Internet domain will lose all of its records - A, MX etc, and will take the records of the Internet domain it is being forwarded to. In this light, you simply can't set up a CNAME record to point your domain to a third-party provider and maintain a working email service with the first hosting company. It is also essential to know that a CNAME record is always a string of words and never a number because it is generally confused with the A record of the domain name being forwarded. One of the main uses of a CNAME record is to direct a domain you own through one company to the servers of another provider in case you have created an Internet site with the latter. This way, the Internet site will appear under your own domain name, not under some subdomain provided by the third-party provider.