What are Dead letter queues?

Answer:

The main use of queue is that you do not need the client and the server running at one
time. So it’s possible that a message will lie in queue for long time until the server or client
picks it up. But there are scenarios where a message is of no use after a certain time. So
these kinds of messages if not delivered within that time span it should not be sent to the
user.
Below is the config snippet which defines for how much time the message should be in
queue.
<bindings>
<netMsmqBinding>
<binding name="MyBindings"
deadLetterQueue="Custom"
customDeadLetterQueue="net.msmq://localhost/private/
ServiceModelSamples"
timeToLive="00:00:02"/>
</netMsmqBinding>