how to send an uneditable PDF form?

I created a form in Adobe Acrobat PRO.

I added a button "SUBMIT", whenever the button is clicked, it attach the integral PDF inside an outlook message so I can send it.

The problem is, the person who receive it, can see the information inside every down menu. He can modifiy the PDF. I just want the PDF to be uneditable.

I can't seem to find the solution