The real point of Inbox Zero was to move you away from “living in your inbox.” (Merlin) Mann said the zero was about “the amount of time an employee’s brain is in [his/her] inbox.” The key to his thinking was that you shouldn’t indulge your inbox as if it were a demanding toddler, allowing it to cry for your attention constantly.
Merlin’s video talk embedded in this article did really change the way I thought about my work (not just my email) when I first saw it many years ago. A recommended watch / listen if by chance you haven’t run across it previously.