Setting up a CNAME record for any of the domain addresses or subdomains you have in the hosting account will allow you to direct 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 domain name it's being forwarded to. In this light, you simply can't set up a CNAME record to redirect your domain name to a third-party provider and maintain a working email service with the first hosting provider. It's also important to note that a CNAME record is always a string of words and not a number as it's commonly confused with the A record of the domain being redirected. One of the main uses of a CNAME record is to point a domain address you own through one company to the servers of another company in case you have created a website with the latter. This way, the site will appear under your own domain, not under some subdomain provided by the third-party provider.