I posted this question on the Google groups site, but did not get a response. From what I can tell, by default, messages do NOT go to the dead letter queue. I need to enable this. I see that I can modify the MSMQMessageBuilder class and set the UseDeadLetterQueue property to true for the message.
However, if I want to use the Nuget package, this option is out. Is there a configuration I can set to enable the DLQ?