Troubleshooting messages stuck in 'Messages awaiting directory lookup' queue

Hi,

So i’ve got to troubleshoot this issue in a very complex multi-domain & multiple exchange organizations & servers..

Internal Messages from Server A in ExchangeORG A , were failing in the categorizer while being processed to be sent to Server B in ExchangeORG B.

Following kb884996 , resolution 2 was valid in my situation, Allow inheritable permissions from parent to propagate to this object check box on Server A object, was missing a Tick..

I set this via ADSIEDIT , noticed of course that the “Exchange Domain Servers” ACE entries , from the other domain were added, and allowed for replication.

After verifying that the ACE’s were propegated & fully replicated, I did a quick restart to MTA, Routing & SMTP services on both servers , and operation was succesfully restored.

Just for extra , this could be also issues with Event Sink that might have been registered and inproperly removed / integrated.. using the smtpreg.vbs , “cscript smtpreg.vbs /enum > Output.txt” i was able to verify that no 3rd party Event Sink were installed or any of Exchange Event Sinks were disabled…