PS to:

Frances Assa: “… One obvious reading of these 5 letters is "I SENT." 

Jansy Mello: What an amazing result: “I sent” - since it seems to fit perfectly into the young man’s illness: his communication is absolutely self-referential and it brings no other message besides the message. The (1964) phrase by Marshall McLuhan that “the medium is the message” is perfectly rendered in this case (and, in part, also in “The Vane Sisters” and in many other Nabokov writings)…

JM: No pun intended in the McLuhan quote. Nevertheless, I said more than I had intended to at first (the medium, as in mediunic states!). Perhaps the spirits included me in their pranks so, here we are: “the medium” is the message, at least, in the novels that function in a self contained world.