Recover deleted items from additional mailbox, MS Exchange

Wondering why "Recover Deleted Items" button is grayed out?

This cheat is tested on Outlook 2013 32-bit version.

Using 32-bit Office on 64-bit system use this:

reg add "HKLM\SOFTWARE\Wow6432Node\Microsoft\Exchange\Client\Options" /v DumpsterAlwaysOn /t REG_DWORD /d 1 /f

For native system use:

reg add "HKLM\SOFTWARE\Microsoft\Exchange\Client\Options" /v DumpsterAlwaysOn /t REG_DWORD /d 1 /f

Close and Re-open Micorosft Outlook.