A rotatable pneumatic feeding head having a vacuum shoe with apertures for picking up an envelope from an envelope stack by negative air pressure. The feeding head has an outer cylinder with holes communicating with the apertures, and an inner cylinder with cutout regions operatively connected to a vacuum pump. The inner cylinder and the outer cylinder are rotated independently of each other such that when they are aligned, a negative pressure is created at the apertures through the cutout regions and the holes. When the inner cylinder and the outer cylinder are out of alignment, the negative pressure is cut off from the apertures. The vacuum shoe is removable so that it can be repaired or replaced when it is damaged or worn.