Ajax form not submitting data to the server, why?

Question

JavaScript

There is a site, on the site a form from one field phone and hidden fields with other values, when sending (pressing a button), the data is sent to phpmail'om and to the server at a different address and the response "successful / unsuccessful" is returned. Everything works, except for sending to another server. Code: pozitive-tlt.ru/mail.js
Chrome does not give any errors, everything seems to be ok, but it does not work.

Answer 1

CORS is a modern browser technology that allows a web page to access resources from another domain.
On the server (PHP) should be:
<?php
header("Access-Control-Allow-Origin: example.com ");
?>

Answer 2

Everything works, except for sending to another server.

Cross Domain Policy?