XFOR: Disabling Inbound ESMTP Advertisement

Under specific circumstances, dependent on a customer's messaging environment, network, and/or topology, it may be necessary to disable automatic advertising of ESMTP extensions when a remote host connects to an Exchange Server 5.0 and/or 5.5 Internet Mail Service. If a host connects to the Internet Mail Service, which is operating normally, the Internet Mail Service sends back the banner: If automatic advertising of ESMTP extensions is disabled, it will instead send back the banner: To disable advertising ESMTP Extensions, a registry change must be made. To do so, follow these steps:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

1. Start Registry Editor (Regedt32.exe).
2. Locate the following key in the registry:

      HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIMC
      \Parameters
     
   						

   NOTE: The above registry key is one path; it has been wrapped for readability.
3. On the Edit menu, click Add Value, and then add the following registry value:

         Value Name: "AdvertiseSMTPExtensions"
         Data Type:  REG_DWORD
         Value:      0
     
   						

4. Quit Registry Editor.
5. Stop and restart the Internet Mail Service.
6. Telnet to the server's port 25, and verify that ESMTP is no longer advertised when connecting to the computer.