Setting up a CNAME record for any one of the domains or subdomains you have within a hosting account will enable you to forward 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 can't set up a CNAME record to point your domain to a third-party company and maintain a functional e-mail service with the first hosting provider. Additionally, it is very important to know that a CNAME record is always a string of words rather than a number because it is commonly mistaken for the A record of the domain address being forwarded. One of the main uses of a CNAME record is to direct a domain address which you own through one company to the servers of some other provider when you have set up a website with the latter. By doing this, the site will appear under your own domain name, not under some subdomain provided by the third-party company.