The msExchSmtpMaxRecipients value has been altered from its default of 64000

[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: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine whether the configured value for the msExchSmtpMaxRecipients attribute has been changed from the default value of 64000. By default, the msExchSmtpMaxRecipients attribute is configured for 64,000 recipients. If the Exchange Server Analyzer finds that this attribute does not have a value of 64000, a non-default configuration message is displayed.

From a security perspective, limiting the maximum size of recipients for each message is a best practice. Each organization should determine for itself what an acceptable value is. Unless you have a reason to configure this value otherwise, it is recommended that you leave the msExchSmtpMaxRecipients attribute set at its default of 64000.

  1. In Exchange System Manager, expand Servers, expand an Exchange server, expand Protocols, and then expand SMTP.

  2. Right-click an SMTP virtual server (for example, Default SMTP Virtual Server) and then select Properties.

  3. Select the Messages tab.

  4. To revert to the default setting of 64000, make sure that the Limit number of recipients per message check box is selected and enter a value of 64000. Alternatively, you can configure this field with any value that you want, or clear the check box to allow an unlimited number of recipients.

  5. Click OK to save the changes and to close the Properties dialog box of the SMTP virtual server.

For more information about SMTP virtual server settings, see the following Microsoft Knowledge Base articles:


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