IBM S544-5343-03 - Manual (Page 54)

5. Load the envelopes with the flap side down and the bottom edge of the envelopes
toward the left side of the auxiliary tray. Make sure you place the bottom edge of
the envelopes against the left side paper guide and under the plastic tab on the
paper guide.
6. Adjust the size guide on the right side of the auxiliary tray to the envelope size.
Make sure you place the top edge of the envelopes under the retaining clip at the
right side of the auxiliary tray.
34 Network Printer 17: User’s Guide