Monetization: We're going to run a hosted version (think Heroku) that developers can use instead of running their own infrastructure. No details to announce now, but feel free to email me if you'd like to join the preview beta. mg@inboxapp.com

Security/Privacy: we take this very, very seriously. I don't want to go into depth right now, but secure email storage has been a primary design goal from inception.

(Note that the open-source sync engine _explicitly_ doesn't have any security/authentication in order to make development easy.)