Setting up a CNAME record for any of the domain addresses or subdomains that you've got within a hosting account will allow you to direct it to a different domain/subdomain. The forwarded Internet domain 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 cannot create a CNAME record to point your domain name to a third-party provider and keep a working e-mail service with the first provider. It's also essential to know that a CNAME record is always a string of words and not a number as it's regularly wrongly identified as the A record of the domain being redirected. One of the primary uses of a CNAME record is to point a domain name that you own through one provider to the servers of some other provider when you have set up a site with the latter. By doing this, the website will appear under your own domain address, not under some subdomain provided by the third-party company.