Shortcuts are one of the best features Mac and OS X have to offer. They make life so much easier. No need to push the mouse or trackpad. I guess I can save up to 4 days a year only by using shortcuts :-)
myMailBoy offers the same shortcuts as Mail.app does for the same tasks…
cmd+O (or return) = Open Message
space = Preview Message
shift+cmd+N = Get All New Message
delete = Delete Message
shift+cmd+U = Marks As Read
shift+alt+cmd+U = Mark All As Read
shift+cmd+J = Mark As Junk Mail