There are two versions of NOD32 for Windows, one for Windows 9x/ME, and another for Windows 2000/XP/2003. Please note that Kerio MailServer only supports the version for Windows 2000/XP/2003.

According to Eset's website, if you are moving from a trial version to a licensed version, you must first uninstall the trial version, reboot the computer, then install the licensed version in order for things to function properly.

To install NOD32:

1. Download NOD32 2.50 and higher, either the trial version or the commercial version. Make sure that you choose the version that's right for your language and operating system. You do not need the version for 'Exchange Server'.
   
2. Install NOD32. (If you need help, there's an installation guide on the NOD32 Manual Page.)
3. Restart your computer when you are asked to.
4. Click on the green-and-white NOD icon in your system tray (near the clock).
5. Click on "AMON" and then click on "Setup."
6. Go to the "Exclusion" tab and select "Add..."
7. Click on "Directory..." and navigate to the location of the Store, Archive and Backup folders for Kerio MailServer.
   Default location: C:\Program Files\Kerio\MailServer\store
8. Click OK in all the dialog boxes that you have opened to do these steps.
9. Click OK in all the dialog boxes and close the NOD32 Control Center.
10. In the NOD32 Control Center, click on "IMON."
11. Click on "Quit." When you are asked if you really want to disable it, say Yes.
12. Close the NOD32 Control Center.

To attach licensed version of NOD32 to Kerio products:

1. Click on “NOD32 System Setup” and then click on "Setup."
2. Go to the "License keys" tab and select "Add..."
3. Select the license file for NOD32. NOD32 for MailServer and Kerio WinRoute requires a special license provided by Eset.
4. Click OK in all the dialog boxes and close the NOD32 Control Center.
5. Restart your computer.
6. Open the Kerio Administration Console and connect to Kerio MailServer.
7. Go to Configuration->Antivirus.
8. Enable option “Use external antivirus” (near the top).
9. Choose "NOD32."
10. Click "Apply" (near the bottom) to save settings.

To attach trial version of NOD32 to Kerio products:

You need a trial license from ESET to enable Nod32 in trial version for Kerio products. To get trial license contact ESET sales department.

NOD32 should now be working properly and scanning your incoming and outgoing email!