Dell 3130cn User's Guide (PDF) - Page 104

NOTICE: Never use envelopes with windows, coated linings, or self-stick adhesives. These lead to paper jams and can cause damage to the printer. NOTE: Ensure that you load an envelope with the flap completely closed. NOTE: If you do not load envelopes in the MPF right after they have been removed from the packaging, they may bulge. To avoid jams, flatten them as shown below when loading them in the MPF. Using the MPF Load only one size and type of print media during a single print job. To achieve the best possible print quality, use only high-quality print media that is designed for use in laser printers. For more guidelines on print media, see "Print Media Guidelines." Do not add or remove print media when there is still print media in the MPF or when the printer is printing from the MPF. This may result in a paper jam. Print media should be loaded with the recommended print side down and the top of the print media going into the MPF first. Do not place objects on the MPF. Also, avoid pressing down or applying excessive force on it. Do not remove any tray while a job is printing from the MPF or Printing is displayed on the operator panel. This may result in a paper jam. The icons on the MPF identify how to load the MPF with paper, and how to turn an envelope for printing. Linking Trays The printer automatically links the trays when you load the same size and type of print media in them. The first tray will be utilized until the media runs out after which the next tray will be used. NOTE: The print media should be the same size and type in each tray. The Multipurpose Feeder (MPF) cannot be linked to any of the tray sources.