I wonder if the name "inbox" is what causes people so much stress. I don't think of it as an actual inbox. It's just where my mail goes - all of it. I read everything, but I don't bother organizing it. Occasionally I'll mark some message as important, or keep a few open so I can get to them later. But most often, I don't.
Search is easy. I don't see the point in organizing my mail.