Here's an entry to the "Mail Art Across the World" organization. This wasn't done by me, although I wouldn't have changed a thing if I had come up with the idea. The top row of letters contain the alphabet from A to Z in both majiscule and miniscule (caps & lower case).
It seems obvious to me that the calligrapher who did this was either guarding against having his entry tossed because the mail carrier would not be able to decipher the script. A lot of people would have difficulty reading the address, but one would think that a mail carrier who's job entails reading many different kinds of penmanship would handle this piece correspondence as second nature.
http://www.maaw.atelier-calligraphie.com/fr/index.php?album=MAAW2009