Creating a CNAME record for any of the domain addresses or subdomains that you have in a hosting account will permit you to point it to a different domain/subdomain. The forwarded Internet domain will lose all its records - A, MX and so on, and will take the records of the Internet domain it's being directed to. In this light, you cannot create a CNAME record to point your domain to a third-party company and keep a working e-mail service with the first provider. Additionally, it is essential to know that a CNAME record is always a string of words and never a number as it's frequently wrongly identified as the A record of the domain address being forwarded. One of the main uses of a CNAME record is to forward a domain name which you own through one company to the servers of another company in case you have created a website with the latter. That way, the Internet site will appear under your own domain name, not under some subdomain provided by the third-party provider.