XADM: Problems Accessing Public Folders in a Mixed Environment

When users attempt to access public folders by expanding the Public Folders item in Microsoft Outlook, they receive the following error message:

Given the following scenario (as an example), a user whose mailbox is homed on an Exchange 2000 server and is pointed to an Exchange Server 5.5 computer for public folders may not be able to connect to the public information store when logging on:

�	An Exchange 2000 server is configured with more than one mailbox store that is located in one or more storage groups.
�	Users located on mailbox store A are pointed to an Exchange 2000 public folder server.
�	Users located on mailbox store B are pointed to an Exchange Server 5.5 public folder server.

Exchange administrators can correct this problem in the following ways:

�	Configure all mailbox stores on the same Exchange 2000 server to point to the same Exchange Server 5.5 computer for public folder information.
�	Configure all mailbox stores on the same Exchange 2000 server to point to a public folder store that is located on the same Exchange 2000 server or to another Exchange 2000 server within the organization, and allow Active Directory Connector (ADC) replication to complete successfully.

This problem occurs because of an Exchange Server 5.5 architectural limitation. Exchange Server 5.5 cannot discern between users that are homed on different mailbox stores on an Exchange 2000 server. When a user connects to an Exchange Server 5.5 computer for public folder information, Exchange Server 5.5 validates that the user is connecting to the correct public folder server. This validation is based on the value for the Home-Public-Server attribute of the private information store object for the Exchange 2000 server, which is stored in the Exchange Server 5.5 directory. When the public folder server attribute is modified for any mailbox store that is located on an Exchange 2000 server, this value is replicated to the Exchange Server 5.5 directory service by means of the ADC, overwriting the previous value for the private information store object. When users attempt to connect, depending upon the current value for the Home-Public-Server attribute, they may be allowed to connect or they may be redirected to another server.