Brother HL-4050CDN EN - Manual (Page 175)

Troubleshooting
166
7
Envelope creases
7
a
Open the back cover.
b
Pull down the two gray levers, one on the left-hand side and one on the
right-hand side, to the envelope position as shown in the illustration below.
c
Close the back cover and re-send the print job.
Note
When you have finished printing, open the back cover and reset the two gray
levers back to the original position.
Examples of poor print quality Recommendation
ABCDEFG
EFGHIJKLMN