Most Exchange admins know how to set the deleted items retention time and how to recover a deleted item, after...
it has been deleted from the Deleted Items folder. But what if it was deleted without going into the Deleted Items folder - or deleted from Public Folders? There is a way.
You need to edit the registry on a workstation to add the following key: HCLMSoftwareMicrosoftExchangeClientOptionsDumpsterAlwaysOn. Set the type to Reg Dword and the value to 1.
Now you will be able to recover deleted mail items (as long as you are within the deleted items retention period) from any folder you have the relevant priveliges.