Assigning a “scan to network” PIN lets you control the sending of scanned items to your computer. You can assign a “scan to network” PIN when you install the printer software for the first time. You can also change it as needed.
From the Finder desktop, double-click the Lexmark 3500-4500 Series folder.
Double-click the Lexmark 3500-4500 Series Center icon.
From the menu, choose Advanced Network Scan Settings.
Select the check box to specify a PIN.
Type in a four-digit PIN. Use a combination of numbers from 1-9.
Click Save.