June 8, 1959 - Just before noon on this day the U.S. Navy submarine USS Barbero surfaced off the northern coast of Florida. It took careful aim at the mainland and launched a customized cruise missile in which the nuclear warhead had been replaced with a bunch of postcards. Twenty minutes later, the missile landed on its target, the Naval Auxiliary Air Station in Mayport, Florida. It was the first official use of "missile mail" by the post office.
The United States Postmaster General Arthur E. Summerfield proclaimed the advent of a new era in mail delivery:
...before man reaches the moon, mail will be delivered within hours from New York to California, to Britain, to India or Australia by guided missiles. We stand on the threshold of rocket mail.
Unfortunately, rocket mail never really caught on. The cost of firing up a cruise missile to deliver a bunch of postcards would be tough to justify.