Today, family members and loved ones overseas can communicate with each other by email and video conferencing. During WWII, the only method to communicate between soldiers, family members, and other loved ones, was to send letters.
By 1942 there was so much mail going back and forth to soldiers overseas that it could take months for mail to be received. The quantity of mailbags was just too overwhelming. Airplanes could only hold so much. Remaining bags would be kept in storage for the next available flight. The main problem was that more and more mail kept coming in faster than it could be sent. The military finally came up with a solution to the problem. It was V-Mail.
V-Mail worked as follows:
1) First soldiers, family members and loved ones would purchase packages of special stationary that contained 50 sheets.
2) Then, the letter was written on the backside only of the sheet. If the letter was more than one-page, additional sheets of V-Mail stationary would have to be sent separately. The address of whom the letter was from was also put on the same side as the letter.
3) The front side also had the "to" and "from" addresses on it. Also, the stamp was affixed on this same side.
4) All V-Mail - despite who it was going to - was then sent by the post office to the Pentagon for processing. There, the letters were opened and the backside photographed at close range. Each letter was photographed on reels of film much like movies were. One reel could hold thousands of letters and weighed less than two pounds. Letters were grouped together on a reel determined by where they were being sent to - France, Germany, etc.
5) Once the reels arrived at their destination, military personnel made enlarged prints of each frame and the letters were delivered to the servicemen addressed to.
V-Mail did much to boost the morale of servicemen and helped to win the war. V-Mail didn't die with the end of the war however. Since after WWII, the technology, originally developed to solve a problem in war, has been used to produce microfilm reels of newspapers, magazines and so forth so common in libraries today.