Setting up a CNAME record for any one of the domain addresses or subdomains that you've got in a hosting account allows you to direct it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX etc, and will take the records of the domain name it is being forwarded to. In this light, you can't set up a CNAME record to forward your domain name to a third-party company and retain a functional email service with the first provider. Also, it is very important to know that a CNAME record is always a string of words and never a number because it is generally confused with the A record of the domain being redirected. One of the primary uses of a CNAME record is to point a domain address you own through one provider to the servers of some other provider assuming you have created an Internet site with the latter. By doing this, the Internet site will appear under your own domain, not under some subdomain provided by the third-party provider.