Mark -- Is the app going to be only a customized mail client that only bypasses the problems of SMTP email delivery and read-tracking? Is it going to REPLACE normal email delivery? I don't see how we can track anything if people are allowed to switch back and forth.
Is it going to provide all of the other web functionality, too?
At this time I am totally unclear on what the app is supposed to do...and not do. By presenting three different (and largely incompatible) user interfaces I am concerned we could end up with a spaghetti-bowl of use cases that will be very difficult to untangle.