Abstract: A foldable letter that can be mailed. The latter encompasses a cut-out paper sheet, one surface of which is intended to receive communications or messages, and the other side of which is intended to receive postal indications, i.e., an address. This letter solves the double problem of finding a form that encourages the writing of letters in the face of the progression of electronic communication equipment and, on the other hand, of enabling easy opening of a folded and sealed letter without tearing it. The proposed solution relates to an appropriate carrier for handwritten communications, and a closure technique offering to the receiver an acceptable letter in its original size. The letter has a square basic shape and includes a rectangular field, the long sides of which are parallel, but not symmetrical, to one of the diagonals of the square.