Envelope creases

Please do the following:

Make sure that envelopes are printed with the back cover (face-up output tray) opened.
Please refer to the FAQ "Print on labels and envelopes from the MP tray".
Check the envelope type and quality.
Please refer to the FAQ "What kind of paper can I use?"
Make sure envelopes are fed only from the MP tray.

FAQ & Fehlerbehebung