Google does a lot of things right, and Gmail is generally one of them. Sometimes, however, you just need a little more from your email experience, and Boxer wants to provide that. It takes the basic Gmail app's functionality – like swipe to delete/archive – and builds on that, bringing even more usefulness to this kind of gesture.
Android Police would like to remind you that email cannot speak. In the event that it does speak, Android Police urges you to disregard its advice.