Brian Fling has written up a terrific post 
on using MailTags and Mail Act-on to stay on top of your email.
He frames it all within the Getting Things Done method of task management, but even if you are not a devotee, you will benefit from the extensive screenshots and the clear way in which the tutorial is designed.
Although he tried using the principles of Feng Shui to manage his email with some success in the past,
by using a couple of simple techniques and some cool software, you can use a less new-agey means to simplify your message stream and get back to work…. The goal is to make the act of archiving a one step process. A big part of getting control of your inbox is to be able to triage and filter information quickly. If if takes you more than a second to store a message, then you are taking too long.
Ten steps or less.
