I can’t love this enough. I’m now using it to do all of my email. It switches from one message to the next instantly, so you don’t have to go back to the inbox in between.
1. Glance at email.
2. Archive, Delete or Reply.
I find I go twice as fast. It’s especially useful for just checking email a few times a day. Then there will be a few messages, and the gains are multiplied.