After attempting to use the HP 5.8 UNI driver, but experiencing random Chinese characters on invoices in accounting, I elected to use the Microsoft print driver which comes with Windows 2012 R2 OS.
We have an HP LaserJet 9050 with an 8-bin Mailbox accessory attached. Once the driver is installed it does not recognize the 8-bin Mailbox but allows me to add it in the Device Settings of the printer properties. However it only shows 4 of the 8 bins (trays) on the server and provides none to the user when printing.
I contemplated trying a older, individual HP driver specifically for the printer, but as they now only provide the UNI, the individual one is much dated (2011), and I hate to install it on the server even to test.