Setting up a CNAME record for each of the domains or subdomains you have in a hosting account allows you to point it to a different domain/subdomain. The forwarded domain address will lose all its records - A, MX and so forth, and will take the records of the Internet domain it's being redirected to. In this light, you can't set up a CNAME record to direct your domain to a third-party provider and maintain a functional 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 name being forwarded. One of the major uses of a CNAME record is to forward a domain address which you own through one company to the servers of another company when you have set up a website with the latter. In this way, the website will appear under your own domain address, not under some subdomain provided by the third-party company.