Illustration by Jesse Harp

1.  BABYLON // 1700 BCE

Don’t be surprised if your mail is coated in fur or feathers. The first envelopes protected documents from the elements and prying eyes. Babylonians wrapped messages in a thin sheet of clay, crimped the edges, and baked it like a pie. Other early envelopes were made of animal skin.

2. MONGOL EMPIRE // 1210

Airmail has changed a little over the years. Genghis Khan relied on carrier pigeons to relay messages of his victories back home in Mongolia, creating a string of messenger posts that stretched across much of Asia and Eastern Europe. Of course, it didn’t stop with Khan—in the 19th century, Reuters news agency also flew stock prices between Aachen and Brussels.

3. BRITAIN // 18th CENTURY

Pack plenty of farthings. Before stamps appeared in the 1840s, recipients paid to get their letters. To save money, some developed secret codes in the addresses so receivers could get messages just by glancing at the envelope. After reading it, they’d simply refuse to accept the letter. Since newspapers traveled for free, people also used them to communicate, underlining words, writing in invisible ink made of milk, or pasting notes over articles.

4. UNITED STATES // 1775

Being elected has its perks. Introduced in 17th-century Great Britain, “franking privileges” allowed government officials to send mail for free just by writing their names on the envelopes. (And it wasn’t just mail—cows, maids, and even feather beds could be “franked.”) The United States instituted the same privilege, but preprinted envelopes didn’t exist, so the process was exhausting—some early members of Congress spent three hours a day signing their names on envelopes (some even hired ghostwriters). Punster Benjamin Franklin signed his name “B. Free Franklin.”

5. HAWAIIAN LEPER COLONIES // 1880

Don’t turn your letters away just because they stink. During plagues, people doused mail from infected regions in boiling vinegar. For lepers in the Molokai colony in Hawaii, only double disinfection would do—mail was treated with sulfur dioxide at the colony and fumigated with formaldehyde after arriving in Honolulu.

6. ALASKA // 1899

Santa isn’t the only one who has used a reindeer delivery service. In the 1800s, the U.S. Postal Service employed the animals to deliver mail on snowy routes in Alaska. The deer worked better than dogs—they pulled the mail (piled on sleds) faster, and postal workers didn’t need to lug any special food. The reindeer just grazed on lichen along the way.

7. GRAND CANYON // 1975 TO PRESENT

Supai is the only town in the Grand Canyon—it’s part of the Havasupai Indian reservation—and mules deliver its mail, carrying about 130 pounds of supplies per trip down an eight-mile trail into the 3000-foot-deep Havasu Canyon.