comprobar correos automaticamente

correos.php

<?php
$curl = curl_init('http://aplicacionesweb.correos.es/localizadorenvios/track.asp?numero=PQ46TX0400262980150010A&idiomaCorreos=es_ES');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
curl_setopt($curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.224 Safari/534.10');
$html = curl_exec($curl);
curl_close($curl);

$dom = new DOMDocument();
@$dom->loadHTML($html);

$xpath = new DOMXPath($dom);
$table = $xpath->query('//table[1]');
$md5 = md5($table->item(0)->textContent);
$test = dirname(__FILE__).'/md5.txt'; 
if (file_exists($test))
{
    $md5f = file_get_contents($test);
    if ($md5 != $md5f)
    {
        // Enviar correo
        mail('[email protected]', 'cambio en estado','http://aplicacionesweb.correos.es/localizadorenvios/track.asp?numero=PQ46TX0400262980150010A&idiomaCorreos=es_ES');
        file_put_contents($test, $md5);
    }
}
else
{
    file_put_contents($test, $md5);
}