Event ID - 6026

Event Id6026
DescriptionThe categorizer failed to expand the dynamic distribution list with address %1:%2 because of a misconfiguration in the directory. The dynamic membership filter string is invalid.
Event InformationAccording to Microsoft:
Exchange System Manager runs by using the administrative credentials of the current user. An administrator with greater administrative credentials than the Exchange computer system account and who previews a query-based distribution group may be accessing Active Directory attributes that are not accessible to the Exchange computer, but that are accessible to the administrator. The administrator will see the correct set of results in the query preview, but the categorizer will run by using the administrative credentials associated with the Exchange computer system account. The categorizer will not be able to retrieve the same set of results. When this behavior occurs, messages are not sent to the query-based distribution group as expected.
The categorizer must have the complete set of recipients before it can submit the message to routing. Therefore, if an error occurs during the expansion of the query-based distribution group to its individual recipients, the categorizer must restart the process. If the error is considered temporary, then the message queues in the Messages Awaiting Directory Lookup queue until all the recipients are successfully resolved. Frequently, this problem is caused by global catalog servers that are unavailable, but it can also be caused by other things.
Reference LinksHow to Troubleshoot Query-Based Distribution Groups

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