XADM: Unable to Connect to Server, Licenses Still Available

When you attempt to connect to a Microsoft Exchange Server computer, you may receive an error message indicating that there are no more client access licenses available. This problem occurs even though the number of users connected to the server does not exceed the number of client access licenses that have been added on the server.

This problem can occur when the "Not for Resale" (NFR) version of Microsoft Windows NT Server or the version of Windows NT Server that is included with the Microsoft Developer Network (MSDN) is installed on the computer running Exchange Server. The NFR version of Windows NT Server is limited to five users and the version of Windows NT Server that is included with MSDN is limited to ten users.

To work around this problem, install the retail version of Windows NT Server. For information about doing so, please see the following article in the Microsoft Knowledge Base:

To determine if you are running the NFR or MSDN version of Windows NT Server, double-click Licensing in Control Panel. If you are running the NFR or MSDN version of Windows NT Server, the following message is displayed: