After revisiting this post, I think there is a simple way to state the idea: The idea is to create a system that tricks email recipients into thinking they wer

After revisiting this post, I think there is a simple way to state the idea: The idea is to create a system that tricks email recipients into thinking they were not expected to receive a given message, despite allowing the recipients full knowledge of how the system works. The first part, however (just tricking the recipients), could be done thousands of ways. For example, spoofed email from a journal service: "Here is a review of what you wrote in your personal, secret journal today: Bob in accounting smells terrible again today, my life sucks... if you believe you received this message in error, please let us know so we can correct our system." So I wonder why it is so necessary to give the recipients full knowledge of how the system works.