Setting up a CNAME record for any one of the domain names or subdomains that you've got in a hosting account allows you to point it to a different domain/subdomain. The forwarded domain will lose all its records - A, MX etc, and will take the records of the domain address it is being redirected to. In this light, you cannot create a CNAME record to point your domain name to a third-party provider and keep a functional email service with the first hosting company. It is also very important to know 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 main uses of a CNAME record is to forward a domain name that you own through one company to the servers of some other provider assuming you have created a site with the latter. This way, the site will appear under your own domain, not under some subdomain provided by the third-party provider.