Setting up a CNAME record for any of the domain names or subdomains that you've got within a hosting account will allow 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 address it is being directed to. In this light, you can't set up a CNAME record to redirect your domain name to a third-party company and maintain a working email service with the first provider. It is also important to note that a CNAME record is always a string of words and not a number because it is often mistaken for the A record of the domain name being redirected. One of the major uses of a CNAME record is to direct a domain which you own through one provider to the servers of another company assuming you have set up a site with the latter. By doing this, the Internet site will appear under your own domain address, not under some subdomain provided by the third-party company.