Load Envelopes You can print on plain paper envelopes in 4 1/8 × 9 1/2 inch (#10) (10.5 × 24.1 cm) size. 1. Open the paper support, pull up the extension, and then tilt it back. 2. Lower the output tray, then open the extension. 3. Flip the feeder guard forward. 4. Squeeze the tab on the edge guide and slide it to the left. 5. Load up to 10 envelopes against the right side. Load them printable side up and flap edge left. Tip:Press each envelope flat before loading it or load one envelope at a time. 6. Slide the edge guide against the envelopes, but not too tightly.