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.

To view and configure the maximum number of recipients

  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: