How to make Mailbox 100 times better
Find Mailbox in your applications folder, right click and select “Show Package Contents”
Navigate to Contents > Resources
Download and unzip this folder. Drag the 3 images into the Resources folder. You will be replacing:
Quit and reopen Mailbox. It should now be 100 times better (assuming you can get to zero inbox).
Note: This is for OS X only.