Microsoft released the Forefront Security for Exchange Server (FSE) with Service Pack 2, an optional but recommended update for FSE customers, including EBS customers. For EBS installations, additional manual steps may be necessary to complete installation. If you selected a separate data partition during Messaging Server installation, steps below apply to you. If you’ve a single partition on your Messaging Server (i.e. only a C: drive), you can skip steps and apply service pack without any additional steps. Install FSE SP2 on EBS Messaging Server with separate data partition: 1. Download and save it locally. Don’t run it at this time. 2. Extract contents by running: setup.exe /x 3. Open folder you extracted files to and copy engineinfo.cab to <DRIVE>:\Windows Essential Business Server\FSEData\Engines folder on your data drive. 4. Run setup.exe from folder you extracted update. 5. Follow prompts of installation wizard to complete setup.

More info: EBS blog