The Internet address (URL) is indeed public, but this web address isn't useful unless a person belongs to a particular Private Email Network (PEN).

Using the administrative controls provided by email2, PEN Administrators are able to restrict access and create "Controlled Access" PENs which do not allow users to join unless they are explicitly invited by a member. Any members that are no longer needed in the Private Email Network, or that are abusing it, can be quickly 'disabled' by the PEN Administrator.

Even when using a relatively open access Private Email Network, all members must register and confirm their identities before using the Private Email Network.

//Edited June 2009