Canon MF 3240 Series Basic Manual page 35

2
When setting a paper, insert the paper into the multi-purpose feeder with
the print side up.
NOTE
When you load paper with a logo on, position the paper with the print side up (logo side) and insert
it so that the top of the paper feeds first in the multi-purpose feeder.
When setting an envelope, insert the envelope into the multi-purpose
feeder with the print side up and the right edge (i.e., closer to the stamp)
first.
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