Most Americans know their ZIP code by heart. They type it into online forms, scribble it on envelopes and memorize it as part of their address. But not everyone knows the original meaning of the term.

Nowadays, people don't send letters to one another when they want to catch up. You may get holiday or birthday cards from your parents, grandparents or other family members and friends, but for the ...

Previously on You’ve Got Mail, we looked at a few services that were designed to speed up the mail at various points along the way. But these improvements were all taking place on the USPS’ side of ...