Recently we had a situation in which a dedicated agent working a channel had retired and the manager over that channel neglected to assign a replacement agent to take it over. This resulted in any message entering the system on that channel being immediately removed from routing mode and put into an "undelivered" queue so that when we did figure out this was happening and added an agent to that category none of the past messages would deliver to them. We attempted to build a Custom Notification to alert us to this situation happening in the future, but there is no option within the query structure to utilize for this purpose. RC support case 20368678 is related to this request.