Creating a CNAME record for each of the domain names or subdomains that you have in the hosting account will enable you to point it to a different domain/subdomain. The forwarded domain name will lose all of its records - A, MX etc, and will take the records of the domain it is being directed to. In this light, you simply can't create a CNAME record to forward your domain name to a third-party company and retain 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 because it is commonly confused with the A record of the domain name being forwarded. One of the major uses of a CNAME record is to direct a domain you own through one company to the servers of some other provider if you have created an Internet site with the latter. That way, the Internet site will appear under your own domain, not under some subdomain provided by the third-party provider.