Abstract: A rectangular mailing envelope is formed with perforations running transversely, that is, in the direction of the width of the envelope, adjacent to one end to define a pull tab. Removal of this pull tab provides a large access opening for easy retrieval of a loose insert which may comprise a single message on a paper or a return envelope together with other documents. By providing transverse perforations to define the tab, the envelopes can be mass-produced at high speeds by moving plies of paper in the direction of the width of the envelopes, the perforated paths running in the direction of movement of the plies so that the perforations can be formed while the plies are in motion.