Código PHP:
<?php
// create a new curl resource
$ch = curl_init();
// set URL and other appropriate options
curl_setopt($ch, CURLOPT_URL, "http://my.site.com/form.php");
// Do a POST
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $_POST);
// grab URL, and print
curl_exec($ch);
?>