I'm not familiar with empower.

I use BB Smart, it's seamless and works with the existing email program. Once in the message list you can change settings and so on. BB Smart has a free trial, maybe you should try them and see which one fits your bill.

BB Smart website.

And I'm not sure if it is still valid, but here is a coupon code to save 15% on BB Smart if you choose to buy it:
BB Smart 15% off coupon code.

****EDIT****: Here's 20% off BB SMART