Setting up a CNAME record for any one of the domain names or subdomains that you have in a hosting account allows you to redirect it to a different domain/subdomain. The forwarded Internet domain will lose all its records - A, MX and so forth, and will take the records of the domain address it's being redirected to. In this light, you can't set up a CNAME record to forward your domain name to a third-party company and keep a functional email service with the first hosting company. Additionally, it is very important to know that a CNAME record is always a string of words and never a number as it is frequently wrongly identified as the A record of the domain being redirected. One of the main uses of a CNAME record is to direct a domain name you own through one provider to the servers of another provider if you have created an Internet site with the latter. This way, the website will appear under your own domain name, not under some subdomain provided by the third-party company.