When you perform an Autodiscover request by using a program that is not Microsoft Outlook, the Autodiscover response contains invalid Outlook Anywhere settings. These settings indicate that the MAPI client should use the NTLM authentication protocol instead of the Negotiate authentication protocol.

Therefore, when you use this kind of client application to connect to a Microsoft Exchange Server 2013 server by using Microsoft Exchange Server MAPI Client and Collaboration Data Objects (MAPI/CDO), the connection fails.


To resolve this issue, install the following cumulative update:

2961810 Cumulative Update 6 for Exchange Server 2013


This issue occurs because the NTLM authentication protocolĀ is used if the client does not identify itself as Microsoft Outlook in the Autodiscover request.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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