Try something like :
Public OldAdd As String
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
OldAdd = Target.Address
End Sub
Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If Range(OldAdd) = Range("A1") And Range(OldAdd).Value = 3 Or Range(OldAdd).Value = 9 Then
Application.Dialogs(xlDialogSendMail).Show
End If
End Sub
You will need to put it in the sheet module ( let me know if you're not sure ).
HTH
Iain