When using a Dynamics MSMQ SendPort, be aware to set the TimeToReachQueue to a higher value then 0! I had created an Itinerary and could not see any messages…It turns out that the TimeToReachQueue interval is somehow ignored when using Dynamic MSMQ send ports.
If the interval specified by the TimeToReachQueue property expires before the message reaches its destination, Message Queuing discards the message in one of two ways. If the message's UseDeadLetterQueue property is true, the message is sent to the dead-letter queue. If UseDeadLetterQueue is false, the message is ignored.
In my case the solution was to set the interval to a higher value than 0, otherwise the message has to be submitted to the queue very quickly! (I noticed this only during bulk/stress-testing so I might slip you attention!)