To enable recover deleted items on mail folders other than the deleted items folder, follow the instructions below:
Please be careful when editing the registry, always create a registry backup before making any changes. If unsure seek help.
1) Click start
2) Click run
3) Type regedit and click ok
4) Expand HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Client\Options
5) Right click the folder options, click new and DWORD value
6) Name the file DumpsterAlwaysOn and amend value to 1
7) Close registry editor
Close Outlook and reopen. To test, click your inbox to highlight, click tools and you should see an option to recover deleted items.