The iPad lets you hold the internet in your hands, and that makes it an amazing tool for handling email. Whether you want to read and reply to messages from the couch, triage your email while on the go, or keep things organized at school or at the office, the iPad can help you do all that or more. You just need the right app. If the built-in Mail doesn't do it for you, there are a bunch of great alternatives in the App Store. But which one is the best?