Setting up a CNAME record for any of the domain names or subdomains you've got within a hosting account allows you to redirect it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX and so on, and will take the records of the Internet domain it is being pointed to. In this light, you simply can't set up a CNAME record to direct your domain name to a third-party company and retain a working email service with the first hosting provider. It is also important to note that a CNAME record is always a string of words rather than a number as it's frequently confused with the A record of the domain being redirected. One of the main uses of a CNAME record is to point a domain that you own through one company to the servers of some other company assuming you have set up a website with the latter. By doing this, the Internet site will appear under your own domain name, not under some subdomain provided by the third-party company.