Riprova così:

codice:
$cont="";
foreach ($_POST as $k=>$a) {$cont.=$k."=".$a."&";};

$fp = fsockopen(gethostbyname("www.studiolegalemuzzini.it"), 80);

$header_send = "POST /data.asp HTTP/1.1\r\n";
$header_send .= "Host: www.studiolegalemuzzini.it\r\n" 
$header_send .= "Content-Type: application/x-www-form-urlencoded\r\n"; 
$header_send .= "Content-Length: " . strlen($cont) . "\r\n\r\n";
$header_send .= "Connection: close\r\n\r\n";
echo $header_send . $cont;
fputs($fp, $header_send . $cont . "\r\n");
echo fgets($fp);
Non so perchè nel codice è finito quel tag html href www.studiolegalemuzzini.it\r\n che non centra nulla.