Setting up a CNAME record for each of the domain names or subdomains that you have in the hosting account will enable you to direct it to a different domain/subdomain. The forwarded domain name will lose all of its records - A, MX and so on, and will take the records of the domain it's being directed to. In this light, you cannot set up a CNAME record to direct your domain name to a third-party provider and maintain a working email service with the first hosting company. Additionally, it is important to note that a CNAME record is always a string of words and never a number as it's frequently confused with the A record of the domain name being forwarded. One of the primary uses of a CNAME record is to direct a domain you own through one provider to the servers of some other company in case you have set up 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 provider.