XADM: Exchange IS Error 1025

The Information Store may report the following error in the Event Log:

This happens when an expired message is in a mailbox that has never been logged on before and the message has a Read Notification Request. While trying to generate the Non-Read Notification (NRN), a logon object is supposed to be created for this mailbox, but at that point no Windows NT User Name is available because this is not a real logon from the user. The logon code tries to cache the Windows NT User Name, but because it does not have the Windows NT User Name, it cannot. At this point, the error code that it used to check whether the Windows NT User Name is already cached is not cleared properly.

Microsoft has confirmed this to a problem in Microsoft Exchange Server, version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.