Reporting: Track requests which have not been responded to

Whenever a message is sent to a requester witihin a request, the NOTIFICATIONSTATUS field in the workorderstates field is populated with "TECH REPLY".

However this includes system emails such as a "Your request has been logged with ID xxxx" which is flagged as a technician reply even though it is system generated.

In MSSQL this:

SELECT distinct "WorkOrder"."WORKORDERID"

FROM (("servicedesk"."dbo"."WorkOrder" "WorkOrder" INNER JOIN "servicedesk"."dbo"."WorkOrderStates" "WorkOrderStates" ON "WorkOrder"."WORKORDERID"="WorkOrderStates"."WORKORDERID") INNER JOIN "servicedesk"."dbo"."AaaUser" "AaaUser" ON "WorkOrder"."REQUESTERID"="AaaUser"."USER_ID") INNER JOIN "servicedesk"."dbo"."WorkOrder_Threaded" "WorkOrder_Threaded" ON "WorkOrderStates"."WORKORDERID"="WorkOrder_Threaded"."WORKORDERID"
WHERE "WorkOrderStates"."STATUSID"<>3
ORDER BY "WorkOrder"."WORKORDERID"

gives me the list of all non-closed request IDs ignoring the thread IDs (due to threads/replies being merged requests)

Is there any other way to track requests which are not closed (WorkOrderStates.STATUSID <> 3) that have not been responded to (excluding by the system account) so I can produce a report showing the requests which need to be chased up?

Or can I link in the system account to the user list somehow?