รบกวนด้วยค่ะ phpmailer ขึ้นว่า Invalid address: คืออะไรหรอคะ

<?php        
require_once("phpmailer/class.phpmailer.php");
header('content-type: text/html; charset=utf-8');

// รับค่าเข้าตัวแปร
$temail = $_GET["txtemail"];
$fname = $_GET["txtname"];
$phone = $_GET["txtphone"];
$ques_comment = $_GET["txtmessages"];

if ($_GET["act"]=="submit") {
	$subject_body = "pretty";
	$message_body = "pretty";
	$message_body .= "<br>: $fname";
	$message_body .= "<br> : $phone";
	$message_body .= "<br> : $femail";
	$message_body .= "<br>: $ques_comment";
	$email = "[email protected]";
        $replyto = "[email protected]";

	//***************************

	$mail = new PHPMailer(true);
        $mail->IsSMTP(); // telling the class to use SMTP
        try {
            $mail->Encoding = "quoted-printable";
            $mail->CharSet = "utf-8";
           
            $mail->SMTPSecure = ''; 
            $mail->Host = 'mail.xx.com'; 
               $mail->Mailer = "smtp"; 
            $mail->Port = '25'; 
            $mail->SMTPAuth = true; 
            $mail->Username = '[email protected]'; 
            $mail->Password = 'xxx'; 

            $mail->AddReplyTo($replyto); 
            $mail->AddAddress($email); 
            $mail->SetFrom($femail); 
            $mail->Subject = $subject_body; 
            $mail->MsgHTML($message_body); 
            // $mail->AddAttachment('image.gif');     
            $mail->Send();

             echo "<script>alert('Send Mail Complete!');</script>";
        }
        catch (phpmailerException $e) {
            echo $e->errorMessage(); // ข้อความ error จาก PHPMailer
        }
        catch (Exception $e) {
            echo $e->getMessage(); // ข้อความ error จากระบบ
        }
}
?>