Creating a CNAME record for any one of the domains or subdomains you have within a hosting account will allow you to redirect it to a different domain/subdomain. The forwarded Internet domain will lose all its records - A, MX etc, and will take the records of the domain it is being redirected to. In this light, you cannot create a CNAME record to direct your domain name to a third-party provider and keep a functional email service with the first hosting provider. Also, it is important to note that a CNAME record is always a string of words rather than a number as it is generally confused with the A record of the domain being redirected. One of the primary uses of a CNAME record is to direct a domain you own through one company to the servers of another provider when you have created 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.
