Canon BJ-230 - Manual (Page 22)

6. Make sure the printer is on-line and start your print operation.
Remove paper from the paper exit support before the count reaches 20
sheets.
Printing On Envelopes
You can stack up to 10 envelopes in the sheet feeder. Before printing on
envelopes, you need to turn on the envelope mode.
Use only commercial, number 10 envelopes, which are 9.5 x 4.1 inches
(241 x 104 mm). (Other envelope sizes are not supported by this
printer.)
NOTE: Do not leave paper stacked in the printer for long periods os time;
longer sheets of paper may become bent or curled over time. This may
cause multiple sheets to feed or the paper may jam.
CAUTION: Some envelopes are not recommended because they may
cause jams or smears or may damage your printer:
T Envelopes with windows, metal clasps, holes, perforations, cutouts,
double flaps, or peel-off sealing strips.
T Envelopes that are specially coated or deeply embossed.
T Envelopes with letters enclosed.