To recover a deleted item, you must have owner rights to the mailbox from which you are recovering deleted items.
To recover deleted items from the Deleted Items folder with Outlook
Open an Outlook client that has access to the mailbox that has deleted items.
Select the Deleted Items folder.
From the Tools menu, select Recover Deleted Items.
Select the item that you want to recover, and then click Recover Selected Items.
To use the DumpsterAlwaysOn registry key to recover hard-deleted items
On the client computer used to perform the deleted items recovery operation, click Start, click Run, type regedit, and then click OK.