Canon imagePRESS C800 Series Troubleshooting Manual page 105

Chapter 1
Pull out and use the auxiliary tray as needed.
3) Take five envelopes, loosen them as shown, and then stack them together. Repeat this step five times for each set of five envelopes.
[Caution] If envelopes are not neatly aligned before being loaded, a problem with the paper supply or a paper jam may occur. Fix any curls or bends before loading
the envelopes.
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