Request with Basic Auth is received from HostAddress:”%1″, HostName:”%2″. Invalid Autodiscover site configuration. To fix the problem either remove Basic Auth or enable SSL.

This Error event indicates that an Autodiscover client (for example, a Microsoft® Outlook® client) is connecting to the Microsoft Exchange Autodiscover service that has the Secure Sockets Layer (SSL) connection disabled and Basic authentication enabled. Autodiscover stops processing this request and returns an HTTP 403 error to the client. We recommend that the Autodiscover client and the Autodiscover service mutually connect by using SSL to prevent spammers from accessing corporate network information. ‘HostName’ in the error message text refers to the Domain Name System (DNS) name of the remote client.

To resolve this error, take one of these steps:

• Enable SSL in the Autodiscover virtual directory on the Exchange Client Access server.

• Use a more secure authentication scheme such as Integrated Windows authentication (also known as NTLM or Kerberos authentication).

For more information about the Autodiscover service, see Managing Autodiscover.

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.