title: How to redirect to an external URL with POST parameters in a controller
body: <p>How can I redirect from a controller to an external URL using POST method and passing some parameters?</p>
  
  <p>Basically I need to do automatically what a form would do. </p>
  
  <p>I found Redirect method in my controller, but it only seems to accept a url string. No method nor parameters.</p>