Creating a CNAME record for any of the domain names or subdomains you've got within a hosting account will allow you to redirect it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX etc, and will take the records of the domain address it's being forwarded to. In this light, you cannot create a CNAME record to direct your domain to a third-party provider and retain a working e-mail service with the first hosting provider. Also, it is very important to know that a CNAME record is always a string of words and not a number because it is often confused with the A record of the domain name being redirected. One of the main uses of a CNAME record is to direct a domain name which you own through one provider to the servers of another provider in case you have created an Internet site with the latter. That way, the website will appear under your own domain name, not under some subdomain provided by the third-party company.