Setting up a CNAME record for each of the domains or subdomains that you've got in the hosting account will permit you to forward 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 domain it is being pointed to. In this light, you simply can't set up a CNAME record to point your domain name to a third-party company and retain a functional email service with the first hosting company. It is also essential to know that a CNAME record is always a string of words rather than a number as it is generally confused with the A record of the domain name being forwarded. One of the major uses of a CNAME record is to forward a domain that you own through one provider to the servers of some other company when you have set up an Internet site with the latter. In this way, the website will appear under your own domain, not under some subdomain provided by the third-party company.