How to recover deleted items in Outlook ?

One of Microsoft Outlook’s hidden features is the ability to recover deleted items, even after you have deleted them from your Deleted Items folder. This feature is not enabled from out-of-the-box, and its activation requires the implementation of a registry tweak using the Registry Editor (regedit).

Remember! If you use the registry editor incorrectly, you might cause serious problems that might require you to reinstall your operating system. Use the registry editor at your own risk.

Backup the registry file. Use instructions provided in section 2 here.
Exit Outlook.
Click Start , click Run and type Regedit to open your Registry Editor.
Browse to My ComputerHKEY_LOCAL_MACHINESoftwareMicrosoftExchangeClientOptions.
On the Edit menu, click New, and then click DWORD Value.
Type DumpsterAlwaysOn.
Set the DWORD value to 1.