It is a comic strip that I started years (123 episodes) ago. It is just that the current adventure is going to be bitcoin related. It is telling a story that a letter has just been delivered to someone. All will make sense and no, there is no man sitting at a computer. That is why I haven't drawn one. 
It seems a nice and unusual start, but as the saying goes, "Don't judge a book by its title."Overall Satoshi's character is shy so I don't think he sends messages as the postal stamp will not be remembered to indicate his address.
Also, the words "to the moon," I expected the message to be in the evening.