Rated 5 out of 5 stars
As someone who now works off of four e-mail addresses, I find this extension not only useful, but virtually necessary. I'm grateful someone finally decided to design it!
The author of the extension is quick to communicate and promptly fixed a minor bug for mac user's when informed about it.
While john2010's suggestions are intriguing, I would find that setting up the rules for such an extension would take too long, whereas this extension allows me just the right amount of hesitation and choice. Moreover, this extension does exactly what it says it does. That's worthy of five stars.