Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry key to determine whether the CustomRejectResponse registry value is present:


The Exchange Server Analyzer displays a warning if the following conditions exist:

Exchange Server 2003 Service Pack 2 (SP2) allows for customization of the server response string that is generated and appended to the non-delivery report (NDR) sent back to the sender. The default response of 550 5.7.1 Requested action not taken: message refused can be changed to provide blocked legitimate users with a meaningful explanation as to why their message was blocked. This explanation can help reduce investigation of false positives and decrease support costs associated with the anti-spam processing.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.
To correct this warning
  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\Software\Microsoft\Exchange\ContentFilter

  3. In the right task pane, right-click the CustomRejectResponse value and select Modify.

  4. Enter the string value you want to use as the custom response, starting the string with 550 5.7.1. For example, you can enter 550 5.7.1 Domain not an allowed sender to set the string to a valid string that will be appended to the NDR.

  5. Save the changes, exit the registry editor, and restart the SMTP service for the changes to take effect.

Before you edit the registry, and for information about how to edit the registry, see Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows registry" (

For more information about intelligent message filtering, see the Exchange Intelligent Message Filter Web site (

For detailed information about how to perform intelligent message filtering tasks, see "Configure Intelligent Message Filtering" in the Exchange Server 2003 SP2 online Help.