Setting up a CNAME record for any one of the domain names or subdomains you've got in the hosting account will allow you to forward it to a different domain/subdomain. The forwarded Internet domain will lose all its records - A, MX etc, and will take the records of the domain name it's being forwarded to. In this light, you can't create a CNAME record to direct your domain name to a third-party provider and retain 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 as it's regularly wrongly identified as the A record of the domain name being forwarded. One of the major uses of a CNAME record is to forward a domain name you own through one company to the servers of another company if you have set up an Internet site with the latter. That way, the website will appear under your own domain, not under some subdomain provided by the third-party provider.