1.When an atom queue GET shape is used, the messages are removed from the queue when the connector shape completes. No subsequent process failure will automatically put the messages back on the queue.
2.If the GET call were in the start shape, then the messages could be retried manually via the platform UI.
3.If there are Message delivery failures,the Dead Letter Queue will be created corresponding to the Destination Queue and the failed messages will be placed in the dead letter queue after 6 retry attempts by the shared queue server of the same atom.
4.The Messages in the Destination Dead Letter Queue can be retried manually from Queue Management tab via the Platfrom UI
5.But if the destination is other than an Atom Queue Server and there is a need to catch the failed messages in case of any failures.The best way to handle this would be to re-queue the failed messages in the catch branch of a try/catch. They can either be placed back on the original queue or they could be placed on some sort of retry queue (if order needs to be preserved).