A series of overlapping envelope blanks are fed into contact with a pull-out roll which engages and accelerates the first blank to separate it from the remaining blanks. From the pull-out roll, the separated blank is fed onto the surface of a rotary aligning wheel. A plurality of aligning pins extend from the surface of the wheel and are positioned in spaced relation around the wheel. The separated blank is fed into contact with the aligning pins forcing the blank with its trailing edge engaged with the pull-out segment to maintain the separated blank aligned on the surface of the wheel. Vacuum ports are positioned on the surface of the wheel adjacent to the aligning pins. The negative pressure from the vacuum ports secures the sheet to the surface of the wheel as the sheet is aligned into a preselected position on the wheel by contact with the pins. The wheel rotates at a lower speed than the pull-out segment and conveys the separated blanks in a radial path to a point on the aligning wheel where each blank is transferred to a folding mechanism where the seal flap of the blank is folded.