Disable FSE using the FSC Utility. Note that your computers will not be protected after FSE is disabled.
Stop the Exchange and Forefront services.
From a command prompt, navigate to the Forefront Security for Exchange Server installation directory. Disable Forefront Security dependencies by typing:
FSCUtility /disable
To confirm that the Forefront Security dependencies have been removed, type:
FSCUtility /status
Restart the Exchange services.
After the installation is complete and the Exchange services have been restarted, verify that mail is flowing.
Enable FSE using the FSC Utility:
Stop the Exchange services.
From a command prompt, navigate to the Forefront Security for Exchange Server installation directory. Enable Forefront Security dependencies by typing:
FSCUtility /enable
To confirm that the Forefront Security dependencies have been reestablished, type:
Run the installer by double-clicking the service pack or rollup executable file.
After the installation is complete and the Exchange and FSE services have been restarted (this occurs automatically during the installation), verify that FSE is working properly.