Setting up a CNAME record for each of the domain addresses or subdomains that you have in a hosting account will allow you to forward it to a different domain/subdomain. The forwarded domain will lose all of its records - A, MX etc, and will take the records of the domain name it is being redirected 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 working e-mail service with the first hosting provider. It is also essential to know that a CNAME record is always a string of words and not a number as it is often wrongly identified as the A record of the domain address being forwarded. One of the main uses of a CNAME record is to direct a domain address you own through one company to the servers of another provider in case you have created a 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.