This is not a security issue. Anyone can add whichever domain they like to their account. If they are the correct owner, then so much the better.
If the owners wish to use our forwarding service, and can't add the domain because someone else added it to their own account, we will do a quick confirmation check, and move the domains to the correct accounts.
Since we support ALL ICANN domains, it would be impossible to have an automatic system check who is allowed to add which domain to their account. The reason for this being, that a lot of different registrars maintain poor and uninformative whois databases, which can not be queried.
SUPPORT - MYDOMAIN.COM
support@mydomain.com -
http://www.mydomain.com