curious about the letterbox plugin. I googled it but not sure which to get it from. 

___________

http://harnly.net/

His site is down at the moment but the plugins are still available. Be sure to follow the install instructions. (included in the download) Just be ready to redownload the plugin if Apple updates mail.app and breaks it. It really should be built in to the application but for some reason Apple has not implemented it. The developer is usually only a few days behind updates.