A review of the United States Postal Service discusses numerous mail-related issues. What is the heaviest thing that you can send in a flat rate box? What happens if you mail a sphere? What are the mysteries of digital postage meters? A look at how modern automation allows you to send a letter 3000 miles for only 42 cents and what security vulnerabilities might exist in that infrastructure. How the new "PLANET" barcode will track all mail in the future. It's all 100 percent legal, but sure to make the mailman wonder. Postal inspectors welcome.