Setting up a CNAME record for each of the domains or subdomains that you have in a hosting account will allow you to direct it to a different domain/subdomain. The forwarded domain will lose all of its records - A, MX and so forth, and will take the records of the domain name it is being directed to. In this light, you simply can't set up a CNAME record to point your domain name to a third-party company and keep a working email service with the first hosting company. Also, it is important to note that a CNAME record is always a string of words rather than a number because it is regularly confused with the A record of the domain name being redirected. One of the primary uses of a CNAME record is to point a domain that you own through one provider to the servers of some other provider 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 provider.