Reference: Message Counters
Message counters gives additional information about the queues: count The total number of messages added to the queue since the server was started countDelta the number of messages added to the queue since the last message counter update depth The current number of messages in the queue depthDelta The overall number of messages added/removed from the queue since the last message counter update. For example, if depthDelta is equal to -10 this means that overall 10 messages have been removed from the queue (e.g. 2 messages were added and 12 were removed) lastAddTimestamp The timestamp of the last time a message was added to the queue udpateTimestamp The timestamp of the last message counter update