MRG Messaging Handling of Client Acknowledgement for orphaned messages

Issue

• If a set of messages are consumed from DURABLE queue with Direct Exchanges with client acknowledgement and if for some reason these in-memroy messages from the application somehow gets destroyed due to system crashing before sending the acknowledgement then is it possible for consumer to re-read these messages from broker ? If yes how ?. Read that if the messages are not acked by the consumer for CLIENT ACKNOWLEDGEMENT then these messages are retained in durable queue until its acked.