Setting up a CNAME record for each of the domains or subdomains that you have in the hosting account will enable you to forward it to a different domain/subdomain. The forwarded domain address will lose all its records - A, MX etc, and will take the records of the domain address it's being redirected to. In this light, you can't set up a CNAME record to direct your domain to a third-party provider and maintain a working email service with the first hosting provider. It's also very important to know that a CNAME record is always a string of words rather than a number as it is regularly confused with the A record of the domain address being forwarded. One of the primary uses of a CNAME record is to point a domain that you own through one company to the servers of another provider assuming you have created a site with the latter. This way, the website will appear under your own domain, not under some subdomain provided by the third-party provider.