Creating a CNAME record for each of the domains or subdomains you have in a 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 name it's being pointed to. In this light, you simply can't set up a CNAME record to point your domain to a third-party company and keep a working e-mail service with the first hosting provider. It's also very important to know that a CNAME record is always a string of words and never a number as it's frequently wrongly identified as the A record of the domain address being redirected. 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 provider if you have created an Internet site with the latter. By doing this, the Internet site will appear under your own domain, not under some subdomain provided by the third-party company.