For advanced users, Postbox's font colors can be customized via a .css hacks which is unsupported. If after using this technique Postbox starts to function in unexpected ways, immediately revert the change.
- Quit or exit Postbox sot that it is no longer running
- Within your profile directory, create a folder called "chrome"
- Download and unzip this userChrome.css.zip file
- Place userChrome.css file within the chrome directory
- Customize the userChrome.css file with the desired font colors
- Start Postbox
Please note that this hack is unsupported and Postbox Technical Support agents cannot answer questions on it's customization or operation, or provide HTML authoring assistance. Thanks for understanding!