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

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

  Select Case FlagWhat
  Case flNextWeek
    dt = DateAdd("d", 7, Date)
    tm = CStr(dt) & " 08:00"
    Icon = olOrangeFlagIcon
  Case flThisEvening
    dt = Date
    tm = CStr(dt) & " 19:00"
    Icon = olYellowFlagIcon
  Case flTomorrow
    dt = DateAdd("d", 1, Date)
    tm = CStr(dt) & " 08:00"
    Icon = olYellowFlagIcon
  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.FlagDueBy = tm
        Mail.FlagIcon = Icon
        Mail.Save
      End If
    Next
  Else
    Set obj = obj.CurrentItem
    If TypeOf obj Is Outlook.MailItem Then
      Set Mail = obj
      Mail.FlagDueBy = tm
      Mail.FlagIcon = Icon
      Mail.Save
    End If
  End If
End Sub