Using a postcard campaign can be doable and is not dead. However you must think like a customer. If they see a postcard in their mailbox what is the liklihood they are going to read it and then call you. I would suggest you choose your most popular service or product and feature that on the postcard with some sort of discount or promotion. Make sure you have your website and contact information on the postcard. You could even create a landing page to specifically track the success of this campaign. Anyone that visits the landing page would have needed to get the information from the postcard.

The problem with traditional marketing versus internet marketing is that the ROI is more complicated to track. If you combine both, you can track your efforts and see what works. You could even try some A/B testing using 2 different versions of your postcards with 2 separate landing pages to see which generates more interest. I hope my information was able to help you out!