HP 8550mfp Service Manual - Page 207

Multi-bin mailbox The multi-bin mailbox is an output unit designed for variable speeds, from 6 to 32 ppm. The multi-bin mailbox holds up to 2,100 sheets distributed in eight 250-sheet face-down bins and one 100-sheet face-up bin. Operating modes The multi-bin mailbox features four intelligent and configurable operating modes.
Mailbox mode - The network administrator can address each bin as an output destination with a name assigned to it. The printer sends a print job to the selected bin. If the assigned bin is full, the printer stops printing.
Job separator mode - Each print job (or copy, if printing multiple original copies) is placed in a separate bin. All multi-bin mailbox bins are used for this purpose, starting with the first facedown bin (at the top). If a multi-bin mailbox bin is full, the printer automatically sends the job to the next available bin. If there are more jobs than bins, the extra jobs will start again at the top facedown bin. This process is seen in the printer software as one logical bin.
Virtual stacker mode - Printed sheets are stacked face down in the bins from the lowest bin to the top bin, regardless of where a print job begins or ends. All printed sheets are sent to the bottom bin until it is full; subsequent sheets are sent to the next upward bin until it is full. This mode of operation takes advantage of the total capacity of the multi-bin mailbox bins. In this mode, the software sees the multi-bin mailbox as one logical bin. When the multi-bin mailbox is full, the printer stops sending paper until all the bins are emptied. EN Multi-bin mailbox 205