Intimate Correspondence by Alan Sobrino/Errant Press

For anyone who likes to read other peoples' mail: Alan Sobrino has written a novel told via five (steamy) letters between Valmont and M. Merteuil, the twisted schemers/seducers from Les Liaisons dangereuses (one of the great novels of letters). To read it, you get each handwritten letter in the mail, one at a time.