Symbolic Name:SmtpSendOutboundAuthenticationFailed
Message:Outbound authentication failed with error %1 for Send connector %2. The authentication mechanism is %3. The target is %4.

This Error event indicates that outbound SMTP authentication on the specified Send connector failed with the specified destination smart host server. Typically, this error indicates an authentication problem on the Send connector, not on the target smart host server. This error is most likely caused when the Send connector is unable to obtain a Kerberos ticket for the target smart host server that is specified in the error message text.

When a Send connector is configured to route outbound messages to a smart host, the following authentication methods are available:

  • None

  • Basic authentication

  • Basic authentication over TLS

  • Exchange Server authentication

  • Externally Secured

In the Exchange Management Console, you set the authentication methods for outbound connections to a smart host on the Configure Smart Host Authentication Settings tab after you click Change on the Network tab of the Send connector properties page.

In the Exchange Management Shell, you set the authentication methods for outbound connections to a smart host by using the SmartHostAuthMechanism parameter on the Set-SendConnector cmdlet.

User Action

To resolve this error, verify that the Send connector and the destination smart host are configured to use a common authentication method with the correct credentials and required certificates.

For more information, see the following topics:

If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.