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 domain name it's being pointed to. In this light, you cannot set up a CNAME record to direct your domain name to a third-party provider and maintain a working email service with the first hosting provider. It is also essential to know that a CNAME record is always a string of words and never a number as it's frequently confused with the A record of the domain name being redirected. One of the primary uses of a CNAME record is to direct a domain name that you own through one company to the servers of another provider in case you have set up an Internet 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 company.