Creating a CNAME record for each of the domains or subdomains that you've got in a hosting account allows you to point it to a different domain/subdomain. The forwarded Internet domain will lose all of its records - A, MX and so on, and will take the records of the Internet domain it is being redirected to. In this light, you cannot set up a CNAME record to direct your domain to a third-party company and retain a working e-mail service with the first provider. Additionally, it is essential to know that a CNAME record is always a string of words rather than a number as it's commonly mistaken for the A record of the domain being forwarded. One of the main uses of a CNAME record is to point a domain address you own through one company to the servers of another company in case you have set up a site with the latter. By doing this, the website will appear under your own domain name, not under some subdomain provided by the third-party provider.