Letterbox is a plugin for Apple's Mail.app that takes advantage of your widescreen monitor. It rearranges the interface into three vertical columns Ã¢â?¬â?? so the message pane is to the right of the message list, rather than below.
What's new in this version:
This version "probably works" under 64-bit Mail, but until I get a 64-bit machine myself, I can't really stand by that claim. It also "hopefully" fixes crashes and hangs, but with all the changes for 64-bit, it could very well have introduced some new ones