Still sending emails through Microsoft Outlook, or any other of the inumerable email services? Do you know who is opening your email, clicking in your email, or what button is being clicked most? If not, you are working more to learn less about your customers!
Let Constant Contact do the work for you. You focus on the message; let Constact Contact worry about the data. And once Constant Contact gives you the information, you're free to apply this new knowledge to your future marketing decisions.