It is a common situation when you get a call from a user who accidentally deleted a message or some other item from their mailbox (like calendar appointment or task item). You recommend straight away checking the deleted items folder and here you are informed that the user has just emptied the Deleted Items folder or has used "Hard delete" (the Shift+Del key combination).
Here comes the moment to use one of the extremely helpful exchange features - "Recover deleted items". Normally Exchange does not actually delete items when the user empties the Deleted Items Container. It marks them with a special flag as purged so they do not display in MS Outlook or in OWA. The messages remain available for a period of time - the default is seven days.
Here you can see how to enable and use the "Recover Deleted Items" feature in MS Outlook. We also demonstrate how to create and apply a Policy in Exchange System Manager which manages the Deleted Items Retention period for the Mailbox Stores in your Exchange organization.