Exchange Transport Service Stops after Installation of Scanmail 8.0 on SBS 2008

After installing the latest version of Trend Micro Scanmail 8.0 on an SBS 2008 server, the Exchange Transport service kept stopping and reporting the following errors in the Application event log:

Event ID: 16023 Source: MSExchangeTransportMicrosoft Exchange couldn’t start transport agents. The Microsoft Exchange Transport service will be stopped. Exception details: Failed to create type ‘TrendMicro.SMEX.hookE12TransportAgent.hookE12RoutingAgentFactory’ from assembly ‘D:Program FilesTrend MicroSmexhookE12TransportAgent.dll’ due to error ‘Invalid agent assembly path.’ …

Event ID: 1052 Source: MSExchange Extensibility

The creation of an agent factory for the agent ‘ScanMail Routing Agent’ failed with error ‘Failed to create type ‘TrendMicro.SMEX.hookE12TransportAgent.hookE12RoutingAgentFactory’ from assembly ‘D:Program FilesTrend MicroSmexhookE12TransportAgent.dll’ due to error ‘Invalid agent assembly path.’.’. Verify that the corresponding transport agent assembly and dependencies with the correct version are installed.

The issues turned out to be a permission issue on the SMEX program file directory.  Exchange uses the Network Service account for the Transport Service credentials but this account didnt get security permissions to the Trend Micro SMEX program folder after install.  Adding the appropriate read permissions did the trick.