Event ID - 9003

Event Id9003
DescriptionCategorizer is temporarily unable to process a message. While processing user smtp:user@contoso.com, the function CPhatCat::CompleteUserMailDrop called SetTargetServer which returned error code 0xc0040559 (A retryable categorizer error occurred. ). ( y:\transmt\src\cat\sinks\phatcat\cptmaildrop.cpp@335 )
Event InformationAccording to Microsoft:

This issue may occur if one of the following conditions is true:
The journaling recipient object has been deleted from the Active Directory directory service.
The Microsoft Exchange Information Store service (Store.exe) is not running or has been disabled on the Exchange Server computer that is the SMTP bridgehead server.
One or more mailbox stores on the SMTP bridgehead server are dismounted.
If messages are to be bifurcated when journaling is enabled, the Information Store service must be running.
To resolve this issue, follow these steps:
1. Make sure that the SMTP bridgehead server has the Information Store service enabled and running. Make sure that the mailbox stores on the SMTP bridgehead server are mounted.
2. Make sure that the journaling recipient object for mailbox stores has not been deleted from Active Directory. To determine the journaling recipient for a mailbox store, follow these steps:
a. In Exchange System Manager, expand the Servers container.
b. Expand the Storage Group container, right-click the mailbox store object to look for message journaling, and then click Properties.
c. On the General tab, view the account that appears immediately under the Archive all messages sent or received by mailboxes on this store check box. This is the account that is being used as the journal recipient.
Note Make sure that you verify the journal recipient for each mailbox store object.
Reference LinksIncoming messages to the back-end server are stuck in the Messages Awaiting Directory Lookup queue on the SMTP bridgehead server in Exchange 2000 Server

Messages remain in the "Messages awaiting directory lookup" SMTP queue in Exchange Server 2003 or in Exchange 2000 Server

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