Setting up a CNAME record for any one of the domain addresses or subdomains that you've got within a hosting account will enable 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 address it's being directed to. In this light, you can't create a CNAME record to redirect your domain to a third-party provider and retain a functional email service with the first provider. Additionally, it is important to note that a CNAME record is always a string of words and never a number as it's frequently confused with the A record of the Internet domain being redirected. One of the primary uses of a CNAME record is to point a domain name which you own through one company 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 address, not under some subdomain provided by the third-party provider.