A method of using reflection of a laser ray (LZ) for measuring the
thickness (e) of a flat mail item (1) consists in nipping the mail item
by means of an elastically deformable member (3) that has a first surface
(4a) in contact with one face of said mail item, and a reflective second
surface (4b) substantially parallel to said first surface, and in
directing the laser ray onto said reflective second surface (4b) for the
purpose of measuring the thickness of the mail item.