Setting up a CNAME record for each of the domain addresses or subdomains that you have in a hosting account will allow you to direct it to a different domain/subdomain. The forwarded domain name will lose all of its records - A, MX and so forth, and will take the records of the domain address it is being directed to. In this light, you can't set up a CNAME record to forward your domain name to a third-party provider and retain a working e-mail service with the first hosting company. Additionally, it is important to note that a CNAME record is always a string of words and not a number as it's regularly confused with the A record of the domain name being redirected. One of the main uses of a CNAME record is to point a domain name which you own through one company to the servers of some other provider when you have set up a website with the latter. In this way, the Internet site will appear under your own domain name, not under some subdomain provided by the third-party company.