File upload component not attached in the email

Hi,

I am working on contact us form and we have created our own form action. When i submit the form i invoke a servlet which is registered with selector .respond.html. The servlet is invoked and sends off the email with our custom process and form fields are sent within email. We also have upload form component which is overridden in apps from libs but the mail sent is missing the attachment. 

If we use the action mail it does what we need and attachment is there but ordering of the form fields is alphabetical and we want the user to receive the form in custom order. Is there a way to achieve it?

Why is the attachment missing? Also, the OOTB mail action is registered as .mail.html and no service/servlet is registered with it so by default SlingPostServlet is handling the submission where can i look code for default POST.jsp. There are multiple references of that file as far as i can see.

Thanks in advance.