This is because you are using the "button press" trigger and technically the button is never pressed. Update the trigger to use the posted email field value instead and it should fix that problem.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.