The SMTP MaxDSNSize value has been manually set

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2007-01-17

The Microsoft® Exchange Server Analyzer Tool reads the following registry subkey to determine if the maximum size of delivery status notification (DSN) messages has been manually overridden:


If the Exchange Server Analyzer finds MaxDSNSize to be present and configured, a non-default configuration message is displayed.

The MaxDSNSize registry value enables a computer running Exchange 2000 Server Service Pack 2 (SP2) or later to remove attachments if a message cannot be delivered. If you enable this option, you can save server and network resources. However, there are drawbacks to this implementation of SMTP attachment stripping.

If you enable this option to strip the attachments from the non-delivery report (NDR), the details that are necessary to display the notification in the preview pane are also stripped, and the originator of the message cannot use the Send Again option. If the originator of the message tries to use the Send Again option from the NDR, the originator of the message receives the following error message:

"Unable to resend the message. The nondelivery report does not contain sufficient information about the original message. To resend the message, open it in your Sent Items folder, click the Actions menu, and click Resend this message."

However, the originator of the message cannot resend the message, even by using the method in the error message. Therefore, it is recommended that you use this option with caution.

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.

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to:

  3. Create a DWORD registry value called MaxDSNSize and set its value data (in bytes) to the desired amount.

  4. Exit the registry editor and restart the SMTP service for the change 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 the MaxDSNSize registry value, see the following Knowledge Base articles:


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