1Use condition to verify if $_POST empty in you main page or index.php to not send the whole page in response ajax
2and verif your AJAX URL
3 $.ajax({
4 type:"POST",
5 url:"http://mywebsite.com/php/send_email.php",
6 .......
7
8index.php
9------------------------
10<?php
11if(empty($_POST)){ ?>
12
13//
14<html>
15the header pages
16the body
17the include pages
18the scripts pages
19the footer
20<?php } ?>