Canon PIXMA MX870 - Manual (Page 114)

Important
Always load paper in the portrait orientation (B). Loading paper in the landscape
orientation (C) can cause paper jams.
Note
Do not load sheets of paper higher than the Load Limit Mark (D).
Note
After loading paper
When using the machine to copy or print without a computer, select the size and type of the
loaded paper for Page size and Type on the print settings screen.
Page 114 of 1127 pages Loading Paper in the Rear Tray