Build Your Constant Contact Email List with WooCommerce. Use the Most Effective Marketing Tool Available with Constant Contact. I bet 80% of you will answer this question the same way: What is the first thing you do when you get to work? Check Email? Yep! Email marketing is one of the most powerful ways to engage with customers and a great revenue-generating tool available for your WooCommerce store. The WooCommerce Constant Contact extension makes it easy to get started with Constant Contact. After a quick setup, a checkbox is added to your checkout page so customers can easily opt-in to your email list. You can also quickly add a signup form anywhere on your site using the built-in widget.