Topic Last Modified: 2006-01-10

The Microsoft® Exchange Server Analyzer Tool queries the Microsoft Internet Information Server (IIS) metabase to enumerate the list of Simple Mail Transport Protocol (SMTP) transport event sink bindings. The Exchange Server Analyzer tries to locate several standard event bindings, based on a list pre-populated in the Exchange Server Analyzer. For each binding, the Exchange Server Analyzer verifies the Component Object Model (COM) registration details in the Registry under the following branch:


The COM registration details contain the full path of the associated .dll file. The Exchange Server Analyzer uses Microsoft Windows® Management Instrumentation (WMI) to locate the .dll file and display its version number. If the Exchange Server Analyzer does not locate the .dll file, the Exchange Server Analyzer displays a warning detailing the file name and path of the missing .dll file

If the Exchange Server Analyzer finds that one or more standard event bindings are missing, the Exchange Server Analyzer generates a warning.

An SMTP transport event occurs when message data is transported into or out of the SMTP service. All messages go through events. These include X.400 and RPC incoming or outgoing messages. One common example of an inbound transport event is the arrival of a message to the SMTP service either over the network or in the SMTP pickup directory. When this transport event occurs, a source for this event notifies the transport event sinks, each of which can take some type of action based on the data content of the message. The system performs no other action with the message data after it passes the message data to the sink until the sink completes its action and returns the message. The sink has exclusive control of the message data and state while it performs this action.

Missing .dll files for transport event sink COM registrations can cause mail flow problems. If the Exchange Server shows symptoms of mail flow problems such as message queuing, verify the presence of the identified .dll files and re-install them if that is required.

To resolve this issue
  1. Use Explorer to manually locate the identified .dll file. Typically, this file will be located in the \Program Files\Exchsrvr\Bin folder.

  2. It is safe to ignore the warning generated by the Exchange Server Analyzer if the following conditions are true:

    • The .dll file is present in the listed folder.

    • The server does not show signs of a mail flow problem.

  3. Copy the missing .dll file from the original Exchange Server installation media if the following conditions are true:

    • The .dll file is not present in the folder listed by the Exchange Server Analyzer.

    • The server shows signs of a mail flow problem.

    Alternatively, reapply the latest Exchange service pack.

  4. Rerun the Exchange Server Analyzer to verify that the warning no longer is displayed.