I previously speculated that a particular letter purporting to be from Al Queda might have been made up as the original was not available, the Internet held few copies analyzing it (essentially one analysis over four publications), and the original was published on April Fool's day.
I jotted off a note to Reuven Paz, the Israeli addressee of that letter asking as to its authenticity. He confirmed that it did exist (the original was in arabic) and was part of a larger series of correspondence. He speculates that his correspondent was arrested or fled Saudi Arabia sometime later in 2004 as the ongoing discourse between the two has stopped.