The Bat! is a powerful, highly configurable, yet easy to use email client. We've designed it especially to help you deal with your growing volume of email as quickly and efficiently as possible, saving much of your precious time. Use all its powerful features at home or at the office to handle your email naturally - the way you want and how you want, simply and directly.
More info:
hxxp://www.ritlabs.com/the_bat/download.html