title: static value in a form
body: <p>I have a form with list of fields :</p>
  
  <ul>
  <li>last name</li>
  <li>email</li>
  <li>country</li>
  <li>message</li>
  </ul>
  
  <p>Before sending the form, i want to joint to it a static value : destination=marketing.
  i don't want it to be visible in my form. how would this be done ? </p>