Note For information on the 3,000-sheet Stapler/Stacker, see HP 3,000- sheet Stapler/Stacker Service Manual Supplement for Paper-Handling Accessories (C4788-90904). C4265-90907 User Installable Accessories 265 4 Secure the mailbox to the stand by tightening the thumb fastener onto the studs beneath the tray extension on the stand. 5 Push the mailbox toward the printer until it snaps in place. 6 Connect the C-Link cable. Plug the power cord into the mailbox and an AC power outlet.