Canon BJ-200ex - Manual (Page 50)

§ The printer beeps once and the indicator
light for the current print mode blinks
rapidly.
§ Press ON LINE to set the printer on-line.
§ Use the envelope mode only when you are loading envelopes; do not
use this mode when loading regular or thick paper.
§ Selecting envelope mode cancels reduction mode (if set).
Preparing the Printer
When you are ready to print on envelopes, follow these
steps to stack envelopes in the sheet feeder. (You can also
manually feed envelopes one at a time.)
1. Set the green paper thickness lever to the right.
2. Set the paper selection lever to the front.