Creating a CNAME record for each of the domains or subdomains that you've got within a hosting account allows you to redirect it to a different domain/subdomain. The forwarded domain address will lose all its records - A, MX and so on, and will take the records of the Internet domain it's being pointed to. In this light, you simply can't set up a CNAME record to direct your domain to a third-party provider and retain a working email service with the first provider. Also, it is very important to know that a CNAME record is always a string of words and not a number as it's generally confused with the A record of the domain name being forwarded. One of the primary uses of a CNAME record is to forward a domain that you own through one company to the servers of another provider when you have created a site with the latter. That way, the site will appear under your own domain, not under some subdomain provided by the third-party company.