Setting up a CNAME record for any of the domain names or subdomains that you've got in the hosting account will allow you to direct it to a different domain/subdomain. The forwarded domain address will lose all of its records - A, MX and so forth, and will take the records of the domain address it's being pointed to. In this light, you cannot create a CNAME record to point your domain to a third-party company and maintain a working e-mail service with the first provider. It is also important to note that a CNAME record is always a string of words rather than a number as it's commonly mistaken for the A record of the Internet domain being forwarded. One of the major uses of a CNAME record is to forward a domain that you own through one company to the servers of some other company when you have created a website with the latter. That way, the website will appear under your own domain name, not under some subdomain provided by the third-party provider.