World War II Victory Mail.

Way before email, during World War II there was v-mail or Victory Mail:

There was no real secret to the v-mail process; in fact it was simple, the soldiers wrote their letters on a form provided and it was then photographed onto microfilm which was simply flown to the USA. A reel of 16mm microfilm could contain 18,000 letters and in terms of bulk and weight the roll of film took up only a fraction of what 18,000 real letters would take. Upon arrival in the USA the letters were printed from the film and then posted onward to the addressee.

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