ho cancellato le righe che mi hai detto.. ecco quello che rimane:
------------------------------------------------------------
require_once 'phpmailer/class.phpmailer.php';

$mail = new PHPMailer();


$mail->From = "miamail@hotmail.com";
$mail->FromName = "io";
$mail->AddAddress("miamail@hotmail.com","pippo");
//la mando a me stesso cosi vedo se arriva

$mail->IsHTML(true); // send as HTML

$mail->Subject = "Here is the subject";
$mail->Body = "This is the HTML body";
$mail->AltBody = "This is the text-only body";
if(!$mail->Send())
{
echo "Message was not sent

";
echo "Mailer Error: " . $mail->ErrorInfo;
exit;
}

echo "Message has been sent";
------------------------------------------------------------

Ecco il risultato:

Message was not sent

Mailer Error: Language string failed to load: instantiate

hai qualche suggerimento? grazie