Setting up a CNAME record for each of the domain names or subdomains that you've got in a hosting account will enable you to forward it to a different domain/subdomain. The forwarded domain name will lose all its records - A, MX and so on, and will take the records of the Internet domain it's being forwarded to. In this light, you cannot set up a CNAME record to redirect your domain name to a third-party company and retain a working e-mail service with the first hosting company. It's also important to note that a CNAME record is always a string of words and never a number as it's generally mistaken for the A record of the domain being redirected. One of the main uses of a CNAME record is to forward a domain address you own through one provider to the servers of some other company in case you have created a website with the latter. That way, the website will appear under your own domain address, not under some subdomain provided by the third-party provider.