If you have a valid license for ESET Mail Security for Microsoft Exchange (EMSX), you can upgrade to the latest version for free.
Open ESET Mail Security.
Press the F5 key on your keyboard to open Advanced setup.
Select Antivirus and antispyware from the Setup tree on the left, deselect Enable Self-defense and click OK.
Restart the server.
Uninstall EMSX version 4.x.
When the download is complete, double-click the installer file to launch the ESET Mail Security for Microsoft Exchange Server installer. A restart will be required during the EMSX 6 installation.