Topic Last Modified: 2006-08-11

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether the value is set to disable Simple Mail Transfer Protocol (SMTP) mailbox addressing:


A value of 1 for the DisableSMTPMailboxAddressing key indicates that SMTP Mailbox Addressing is disabled (true) whereas a value of 0 indicates that SMTP mailbox addressing is not disabled (false).

If the Exchange Server Analyzer determines that the value of the DisableSMTPMailboxAddressing key is set to disable SMTP mailbox addressing with a value of 1, the Exchange Server Analyzer displays a warning.

This error indicates that SMTP mailbox addressing is disabled. This can cause synchronization errors for Microsoft Exchange ActiveSync clients that connect to this server.

To address this warning, set the value of the DisableSMTPMailboxAddressing key to 0.

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 modify the value for the DisableSMTPMailboxAddressing key
  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to:


  1. In the right pane, locate and double-click DisableSMTPMailboxAddressing

  2. Change the value from 1 to 0.

  3. Close the registry editor, and restart the Server service for the change to take effect.

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

For more information about the synchronization error associated with this warning, see Microsoft Knowledge Base article 886346, "You receive an HTTP_500 error message when you synchronize your mobile device with Microsoft Exchange Server 2003" (