MSExchangeISPublic Event 9551 is logged after you grant Public Folder permissions to an Exchange Server 5.5 user

If you are working in a mixed-mode environment where Microsoft Exchange 2000 Server or Microsoft Exchange Server 2003 and Microsoft Exchange Server 5.5 are installed in separate Active Directory domains, when you grant an Exchange Server 5.5 user permissions to a public folder on the Exchange 2000 or Exchange 2003 computer, the following events are logged in the Application log.

Event 1

Event 2

When an Exchange Server 5.5 user tries to access the public folder, he or she may receive one of the following error messages.

Error message 1

Error message 2

This issue may occur because any user object that is mailbox-enabled must have the msExchUserAccountControl attribute stamped on it by Recipient Update Service, and the attribute value must be set to 0. If the user object is not configured in this way, it is treated as mailbox-disabled.

By default, Recipient Update Service is not available in an Active Directory domain that has only an Exchange Server 5.5 computer. Therefore, the user object in Active Directory that is associated with the mailbox on the Exchange Server 5.5 computer does not have the msExchUserAccountControl attribute set.

When you grant an Exchange Server 5.5 user permissions to a public folder in Exchange 2000 or Exchange 2003, the information store on the Exchange 2000 or Exchange 2003 computer assigns the distinguished name of this mailbox to that public folder. The Exchange 2000 or Exchange 2003 information store tries to upgrade this Exchange Server 5.5 distinguished name to a Windows security identifier (SID). If the Active Directory user object that is associated with this mailbox does not have the msExchUserAccountControl attribute set, when the information store reads this attribute, and then does not upgrade the Exchange Server 5.5 distinguished name to a Windows SID, the information store generates the events that are described in the "Symptoms" section.

To resolve this issue, run Exchange 2000 or Exchange 2003 Setup with the /domainprep switch in the domain in which the Exchange Server 5.5 computer resides. Then, create an additional Recipient Update Service for that same domain . This Recipient Update Service instance will populate the msExchUserAccountControl attribute for all mailbox-enabled user objects. To create the additional Recipient Update Service, follow these steps:

1. Start Exchange System Manager.
2. Right-click the Recipient Update Services container, and then click New Recipient Update Service.
3. Enter the domain where the Exchange Server 5.5 computer resides as the object to be updated by this service.
4. Enter the name of the Exchange 2000 or Exchange 2003 computer where you want to run this service.
5. Click OK.

For more information about running setup /domainprep, click the following article number to view the article in the Microsoft Knowledge Base: For additional information about the Exchange Recipient Update Service, click the following article number to view the article in the Microsoft Knowledge Base: