Add JavaScript to invoke the iframe form POST. Place the JavaScript after the closing
</body>
 element as shown in this example. The JavaScript invokes the iframe form POST automatically when the window loads. You can also choose to submit the form at a different time, but you must submit it before requesting the check enrollment service.
JavaScript to Invoke the Iframe Form POST 
 <script>
window.onload = function() { 
var cardinalCollectionForm = document.querySelector('#cardinal_collection_form'); 
if(cardinalCollectionForm) // form exists 
cardinalCollectionForm.submit();
}
</script>