New Testament theologians have long known that the Apostle Paul wrote some of his epistles while in prison. It wasn't until just recently, however, that they came across some historical references to how he managed to smuggle these inspired messages out of prison and get them to his intended recipients.
From deep within one of his many dungeon incarcerations, Paul was able to gain access to the bow and arrow of one of the guards. After affixing his epistle to the arrow's shaft, Paul launched it out through a high window and out to freedom, where a waiting disciple collected it and delivered it.
Thus was born the first guided missive.