You can load
one envelope or one sheet of paper or card stock in the rear feed
these paper loading guidelines:
Load only one
sheet or one envelope at a time.
Load paper short
edge first, no matter which way your document faces.
printable side faceup.
or pre-printed paper top edge first.
Check the paper
package for any additional loading instructions.
Note: You can
load a sheet of binder paper with holes on one of the long edges,
but not for automatic 2-sided printing.