title: NServiceBus MSMQ messages intermittently get stuck on the Outgoing Queue
body: <p>We have a Pub / Sub system based on NServiceBus, where we have intermittent issues with messages getting stuck on the Publishers outgoing queue indefinitely, rather than being transmitted to the Subscribers input queues.</p>
  
  <p>Points to note:</p>
  
  <ol>
  <li>When we restart the Publisher Service and Subscriber services, message flow resumes normally for a while.</li>
  <li>The problem seems to occur more often if a sustained period of time between messages occurs.</li>
  <li>The publisher service resides on the LAN, the subscribers on the otherside of a firewall.</li>
  <li>Some messages get through! As mentioned after service restarts, things go fine for a while. </li>
  <li>Using QueueExplorer, I can see the messages on the Outgoing queue have a state of WAITING.</li>
  </ol>
  
  <p>Annoyingly our development environment does not exhibit this behaviour, but then again the publisher and subscribers all reside on the same LAN in this environment.</p>