If you could automatically have a history of emails from people you know, do you still need to know if a new email is from a person you know for you to manually process it? And if so, why?
I'm not so sure if I would want to destroy an email with reckless abandon if it's from someone I don't know but who know me. Maybe they want to get in touch about some of my work.
By the way, I liked the idea of expiration filters on emails.