Procedure to recover shift deleted [permanently deleted] mails from Microsoft Outlook.
1) First go to Run and type regedit
2) Go to: \HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\EXCHANGE\CLIENT\OPTIONS registry key.
3) Right click options and add new DWORD VALUE (data type is REG_DWORD) and then right click and rename to DumpsterAlwaysOn. It is case sensitive.
4) Then rights click and modify and make the value 1 to turn the Recover Deleted Items menu choice on for all folders or enter 0 to turn it off.
5) Then go to Outlook , choose "Recover deleted items" option from the Tools Menu to get back your "permanently deleted" mails!
Note: This procedure can recover mails which were deleted by pressing shift+del in the past 30 days.
Hope this is useful to some of us.