Basically, you write/type and scan an "old-school" letter (vice e-mail), or write a letter on the
website .
Basically, it sends the "hand-written" letter straight from your computer to the Marine's nearest post office. The "forward" post office prints, folds, and addresses the mail, which is then delivered to the Marine at mail call. This cuts out weeks/months of waiting for the letter to go through the regular postal service.
Never tried it, but I'm interested to see how it works.