You can extend the message retention period in Simple Message Queue (formerly MNS) by configuring the MessageRetentionPeriod property.
Set the MessageRetentionPeriod property in the SetQueueAttributes method to specify how long, in seconds, a message is retained in a queue. The default retention period is 345,600 seconds (4 days). Valid values: 60 seconds (1 minute) to 604,800 seconds (7 days).