Neat. Glad there are still people not treating email as a solved problem. I tossed my address in for an invite.. Meanwhile.. Is there a security whitepaper or writeup somewhere? Handing over the keys to your email account isn't something I'm eager to do without some confidence in your product :)
[Edit] Also... please paste the "if sender == 'pg@ycombinator.com':" condition that I want to believe is in your codebase.