Canon MF55DD Series Basic Manual page 42

8
Pinch and slide the width slide guides to fit the envelopes.
2
Make sure the envelopes do not exceed the load limit mark.
9
Insert the cassette into the machine.
NOTE
If you do not completely insert the cassette into the machine, paper jams may occur.
2-10 Loading Paper
Hooks
Hook
Load limit
mark
Hook