Load Envelopes You can print on plain paper envelopes in 4 1/8 × 9 1/2 inch (#10) size. 1. Open the paper support. 2. Open the output tray and pull out the extensions. 3. Press in the tab on the edge guide and slide it left. 4. 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. 5. Slide the edge guide to the edge of the envelopes, but not too tightly. See also: Load Paper for Photos Load Paper for Documents