Public Enum FlagWhatEnum
  flNextWeek = 0
  flThisEvening = 1
  flTomorrow = 2
End Enum

Public Sub FlagNextWeek()
  FlagItem flNextWeek
End Sub

Public Sub FlagThisEvening()
  FlagItem flThisEvening
End Sub

Public Sub FlagTomorrow()
  FlagItem flTomorrow
End Sub

Public Sub FlagItem(FlagWhat As FlagWhatEnum)
  Dim Mail As Outlook.MailItem
  Dim obj As Object
  Dim Sel As Outlook.Selection
  Dim Item As Object
  Dim i&
  Dim dt As Date
  Dim tm As String
  Dim Icon As OlMarkInterval

  Select Case FlagWhat
  Case flNextWeek
    dt = DateAdd("d", 7, Date)
    tm = CStr(dt) & " 08:00"
    Icon = olMarkNextWeek
  Case flThisEvening
    dt = Date
    tm = CStr(dt) & " 19:00"
    Icon = olMarkToday
  Case flTomorrow
    dt = DateAdd("d", 1, Date)
    tm = CStr(dt) & " 08:00"
    Icon = olMarkTomorrow
  End Select

  Set obj = Application.ActiveWindow
  If TypeOf obj Is Outlook.Explorer Then
    Set Sel = obj.Selection
    For i = 1 To Sel.Count
      Set obj = Sel(i)
      If TypeOf obj Is Outlook.MailItem Then
        Set Mail = obj
        Mail.MarkAsTask Icon
        Mail.TaskStartDate = tm
        Mail.TaskDueDate = tm
        Mail.Save
      End If
    Next

  Else
    Set obj = obj.CurrentItem
    If TypeOf obj Is Outlook.MailItem Then
      Set Mail = obj
      Mail.MarkAsTask olMarkNextWeek
      Mail.TaskStartDate = tm
      Mail.TaskDueDate = tm
      Mail.Save
    End If
  End If
End Sub