Out-of-office automaticly set for Outlook 2010 for inside & outside organisation

Question

I am currently able to automatically enable OOO (out-of-office) automatically when Outlook is closed.

I have the following code which enables OOO when I close outlook, it currently works only for internal emails (replying to emails received from inside the organisation), but it doesnt work for emails received outside the organisation (like if I send an email from my hotmail account to test it, I get no automated reply).

Any ideas on how to fix this?

Private Sub Application_Quit()
  OutOfOffice True
End Sub

Private Sub Application_Startup()
  OutOfOffice False
End Sub

Sub OutOfOffice(bolState As Boolean)
  Const PR_OOF_STATE = "http://schemas.microsoft.com/mapi/proptag/0x661D000B"
  Dim olkIS As Outlook.Store, olkPA As Outlook.PropertyAccessor
  For Each olkIS In Session.Stores
    If olkIS.ExchangeStoreType = olPrimaryExchangeMailbox Then
        Set olkPA = olkIS.PropertyAccessor
        olkPA.SetProperty PR_OOF_STATE, bolState
    End If
  Next
  Set olkIS = Nothing
  Set olkPA = Nothing
End Sub

Thank you very much for any help you can provide...

Olga p.s. original source: http://www.experts-exchange.com/Software/Office_Productivity/Groupware/Outlook/A_3487-Automating-Out-of-Office-in-Outlook.html