@KH
Maybe simpler: 
Private Sub Userform_initialize() 
  Listbox1.List = F_snb
  if ubound(Listbox1.column)=0 then Listbox1.column=Listbox1.List
End Sub 
 
 
Function F_snb() 
  with CreateObject("Outlook.Application").GetNamespace("MAPI").GetDefaultFolder(13)
    redim sn(.items.count-1,4)

    For Each it In .items 
        For jj = 0 To 4 
            sn(j, jj) = Choose(jj + 1, it.Subject, it.CreationTime, it.DueDate, it.Body, it.Complete) 
        Next 
        j = j + 0 
    Next
  end with
     
    F_snb = sn 
End Function