Canon G3000 Series Online Manual page 120

4. Slide the paper guides (D) to open them, and load the envelopes in the center of the rear
tray WITH THE ADDRESS SIDE FACING YOU.
The folded flap of the envelope will be faced down on the left side.
Up to 10 envelopes can be loaded at a time.
5. Slide the paper guides (D) to align them with both sides of envelopes.
Do not slide the paper guides too hard against the envelopes. The envelopes may not be fed properly.
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