Canon LASER SHOT LBP-1210 User Manual page 37

2.
Most applications allow you to choose which way envelopes feed into the
printer. Make sure your printer settings before you print.
When using C5-size envelopes, remove any stiffness by lightly flexing
both edges of the envelope.
20
Paper Handling
Adjust the paper guides on the right, left, and front to the size of the
envelope.
Chapter 2