@Mahir; şu şekilde dener misin ekrana ne yazıcak?

$mail = new PHPMailer();
$mail->IsSMTP(); 
$mail->Host       = "mail.aracmuayenerandevual.net";
$mail->SMTPAuth   = true;                  // enable SMTP authentication
$mail->Username   = "admin@aracmuayenerandevual.net";  // username
$mail->Password   = "**********";            // password
$mail->CharSet = 'UTF-8';
$mail->AddReplyTo('randevu@aracmuayenerandevual.net', 'Randevu');
$mail->SetFrom('randevu@aracmuayenerandevual.net', 'Randevu');
$mail->AddAddress("randevu@aracmuayenerandevual.net", "Oguzhan");		
$mail->Subject = $_SESSION["siparis_adsoyad"];
$mail->MsgHTML($_SESSION['mail_icerik']);
if($mail->Send())
{
	echo "gönderildi.";
}
else
{
	echo $mail->ErrorInfo;
}