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
You can set he message's AcknowledgeType property to request that Message Queuing send a negative acknowledgment message back to the sending application if the message does not arrive before the timer expires.
If the TimeToReachQueue property is set to 0 seconds, Message Queuing tries once to send the message to its destination—if the queue is waiting for the message. If the queue is local, the message always reaches it.
If the value specified by the TimeToReachQueue property is greater than the value specified by the TimeToBeReceived property, TimeToBeReceived takes precedence.
When several messages are sent in a single transaction, Message Queuing uses the TimeToReachQueue property of the first message.