Outlook users prompted for credentials when they switch from a LAN to a WAN

Applies to: Microsoft Office Outlook 2007Microsoft Outlook 2010Outlook 2013

Symptoms


Assume that domain users connect to Microsoft Exchange Server by using Microsoft Outlook. The Outlook Anywhere feature is enabled in their Outlook profiles. When the domain users switch from using the LAN to using a wide area network (WAN), they are prompted for credentials by Outlook.

Cause


This issue occurs when the client authentication method of Outlook Anywhere is set to Basic Authentication on the Exchange server.

When the user switches to another network, Outlook may change the connection type from TCP to HTTPS. If the client authentication method of Outlook Anywhere is set to Basic Authentication, the user is prompted for credentials.

Resolution


To resolve this issue, set the client authentication method of Outlook Anywhere to NTLM Authentication on the Exchange server.

More Information


For more information about how to configure Outlook Anywhere on an Exchange server, go to the following Microsoft websites: