If SmartThru 4 refuses to work on your modern computer despite the troubleshooting steps above, you do not need to throw away the printer. You can use built-in Windows tools to scan, provided the basic printer driver is installed.

Given the age of the SCX-4521F (released circa 2006–2009), there may come a time when SmartThru 4 will not run on future versions of Windows. Here are three alternatives.

If the official package doesn't include “SmartThru 4” but you need scanning:

Do not search for “SmartThru 4” alone. Instead, download the official full driver package from HP’s support site for the SCX-4521F.
Once installed, the scanning function will be available through Samsung Scan Assistant (not necessarily branded SmartThru 4). If the interface is essential to you, consider using VMware or a legacy Windows XP/7 virtual machine with the original Samsung CD software.

Before downloading, it is important to understand what this software does:

Important Note for Windows 10/11 Users: SmartThru 4 was designed for Windows XP, Vista, and Windows 7. On Windows 10 or 11, you may encounter compatibility warnings. If you only need basic scanning, Windows has a built-in app called "Windows Fax and Scan." However, if you need the specific Samsung features (like OCR or direct email scanning), you must use SmartThru 4.