Ok yesterday, I ran into an issue where store.exe on one of my CCR Cluster was repeatedly crashing, with no related event logs being generated in the Application Event Log.  I called MS Premier Support and after running a debugeer on store.exe the log was related to  KnowledgeBase article 959135, it was necessary to create a registry key called “Search Folder Nesting Level” in HKLM\System\CCS\Services\MSExchangeIS\ParamtersSystem and set it to a value of 500 and a registry key called “Validate Search Folder Restriction” in HKLM\System\CCS\Services\MSExchangeIS\ParametersSystem and set the value to 1

Today I received a call that messages to one of our key users was bouncing with a rather weird NDR notificiation

:#550 5.3.4 STOREDRV.Deliver: message exceeds fixed system limits. The following information should help identify the cause: “MapiExceptionTooComplex:16.18969:890F0000, ….

I moved the mailbox to another DB and got an error but the mailbox moved.

The next recommended step is to still run ISINTEG on the DB to get rid of the corrupt data.