Setting up a CNAME record for each of the domain names or subdomains that you've got in a hosting account will allow you to redirect it to a different domain/subdomain. The forwarded domain address will lose all of its records - A, MX etc, and will take the records of the Internet domain it's being directed to. In this light, you simply can't set up a CNAME record to redirect your domain name to a third-party company and retain a working e-mail service with the first hosting company. Also, it is very important 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 name being redirected. One of the primary uses of a CNAME record is to point a domain address you own through one company to the servers of another company if you have set up a site with the latter. That way, the website will appear under your own domain address, not under some subdomain provided by the third-party company.