Creating a CNAME record for any of the domains or subdomains you have within a hosting account will permit you to forward it to a different domain/subdomain. The forwarded Internet domain 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 can't create a CNAME record to forward your domain to a third-party company and keep a functional e-mail service with the first hosting company. Also, it is very important to know that a CNAME record is always a string of words and not a number as it's frequently mistaken for the A record of the domain being forwarded. One of the main uses of a CNAME record is to direct a domain name which you own through one company to the servers of some other company in case you have created an Internet site with the latter. In this way, the website will appear under your own domain address, not under some subdomain provided by the third-party company.