What is Postbox?
Postbox is a desktop email client, news client and feed reader for Windows and OS X. Written and sold by Postbox, Inc, it was launched at the TechCrunch 50 conference in 2008.
Postbox was founded and staffed by several former developers from Mozilla. The software was built using Mozilla's Gecko browser engine, and was initially based on Thunderbird, Mozilla's own e-mail software.