//need to send 12 messages; 1 message is dequeued and actor waits on lock,
//2nd to 11th messages are put on the queue
//12th message is sent to dead letter.
//need to send 12 messages; 1 message is dequeued and actor waits on lock,
//2nd to 11th messages are put on the queue
//12th message is sent to dead letter.