Lexmark All in One Printer - Manual (Page 61)

61 Loading Print Materials
Envelope feeder
Guidelines • Load only one size of envelopes at a time in the envelope
feeder.
• To achieve the best possible print quality, use only high-quality
print material that is designed for use in laser printers. For
more information, see
“Envelope guidelines” on page 33 .
• Do not place objects on the envelope feeder. Also, avoid
pressing down or applying excessive force on it.