A parked domain is another domain that points to your existing domain's content. While you can create email accounts for a parked domain, it cannot have its own unique content or subdomains.
If you park domain2.com on top of domain1.com, both URL's below will show the exact same content:
http://domain1.com
http://domain2.com
Please see our article "How to Park A Domain" for instructions on setting up parked domains.
