Setting up a CNAME record for any of the domains or subdomains you've got in a hosting account will enable you to point it to a different domain/subdomain. The forwarded domain will lose all its records - A, MX and so on, and will take the records of the domain name it is being directed to. In this light, you can't set up a CNAME record to point your domain name to a third-party company and keep a working email service with the first hosting company. Additionally, it is essential to know that a CNAME record is always a string of words rather than a number as it's commonly wrongly identified as the A record of the Internet domain being forwarded. One of the major uses of a CNAME record is to direct a domain address that you own through one provider to the servers of some other company assuming you have created an Internet site with the latter. This way, the site will appear under your own domain address, not under some subdomain provided by the third-party provider.