Dell 1815dn Multifunction Mono Laser Printer - Manual (Page 85)

Selecting an Output Location
The printer has two output locations; the output tray (face down) and the rear cover (face up).
To use the output tray, make sure that the rear cover is closed. To use the rear cover, open it.
NOTE: If paper coming out of the output tray has problems, such as excessive curl, try printing to the rear cover.
NOTE: To avoid paper jams, do not open or close the rear cover while the printer is printing.
Printing to the Output Tray (Face down)
The output tray collects printed paper face-down, in correct order. The tray should be used for most print jobs.
If necessary, expand the paper output extension to keep print media from falling off the output tray.
Printing to the Rear Cover (Face up)
Using the rear cover, paper comes out of the printer face up.
Printing from the bypass tray to the rear cover provides a straight paper path. Using the rear cover might improve the output quality with special materials.
To use the rear cover:
Open the rear cover by pulling it.