In her curious series of playfully-addressed envelopes, Harriet Russell issues forth a challenge to Royal Mail postal workers: How far are you willing to go to deliver my mail?

The illustrator wrote 130 letters to herself, cleverly disguising the addresses on the envelopes using dot-to-dot drawings, crossword puzzles, cartoons, and even color perception tests. While we tend to think of postal workers with disdain, her results were astonishing--only ten letters weren't delivered.

What's more, Harriet Russell helped continue a family tradition she wasn't aware of until she'd already begun sending the letters, according to the Independent. Her work, combined with that of her family, has since been published in a book called "Envelopes: A Puzzling Journey Through the Royal Mail."