For example, a certified listening transport is receiving certified delivery of the subject FOO from a certified sender named
BAZ. After receiving and queuing message number
32, the next message to arrive is message
35. Certified delivery software holds message
35 until it can first queue messages
33 and
34; once these messages arrive, the listening transport queues events for each of the three messages in the proper order.
Meanwhile, the certified listening transport automatically requests retransmission of messages 33 and
34 from
BAZ. In a case where the time limit on those messages has expired—so
BAZ no longer has them in its ledger—the certified listener transport presents a
DELIVERY.UNAVAILABLE advisory, indicating that messages
33 and
34 are no longer available. Then it queues an event for message
35.
