you also need to look to Red Flag guidelines if you are going to use a 3rd party change of address system for forwarding mail, such as US Postal National Change of Address (NCOA) database, which has some stipulations to follow to help detect fraudulent change of address processes.
as far as relying on the client, that is tough. one thing our contact center does is validates with every caller that we have their correct address, not an easy task. you would be surprised the number of clients that balk at confirming their address.
_________________________
Providing alternative truths since the invention of time