[Dick comes to the door of Tom.]
Dick: Hey Tom, I see that you don't have a mailbox. I have a few hundred extras down the street, would you like to use one on the condition that I might analyze who is sending you mail and the like? It's really secure and it's all the rage in the city you can store 2000 pounds of mail forever blah blah blah. You should really use it!
Tom: Sure Dick, it's a real help to have an address for bills, personal correspondence, etc. And I can use it to establish residency and so on.
[Tom puts the address in his letterhead, tells everyone to use it, makes several job applications with it, etc. He uses it for everything. Every service he uses authenticates him by his access to this box.]
[One morning Tom goes out to his box and sees it has been padlocked. After a great deal of searching, Tom finds an unofficial contact for Dick.]
Tom: Hey Dick, can you unlock the box for me? I am expecting a check, a letter from my daughter, etc.
Dick: Sorry, I can't do that. And I can't tell you why. What did you expect for free? Anyway, how did you get this number?