php phpmailer总是去hotmail垃圾文件夹任何人都可以解决

Question

<?php   

    $to=$_POST['email'];
    $pwd=$_POST['pwd'];

    $activate_code = md5($_POST['pwd'] . $_POST['email'] . time()); 

    $subject  = "卓能脹戶啟動程序" ;
    $body ="親愛的 [$username]  ： <br />" . 
       "歡迎加入卓能會員網站！ <br />" .
       "請利用以下網址啟動您的帳號，才能完成註冊程序，" .
       "<a href=http://www.domain.com/activate.php?code=$gencode>http://www.domain.com/activate.php?code=$gencode</a>  " . 
       "勿直接回覆此信　。 <br />" .
       "<br /> 開啟動成功後您會員帳號即可立即使用。";

    include("PHPMailer/class.phpmailer.php");
    $mail= new PHPMailer(); 
    $mail->IsSMTP(); 
    $mail->SMTPAuth = true;
    $mail->Host = "smtp.domain.com"; 
    $mail->Port = 25;  
    $mail->CharSet = "utf-8";
    $mail->Username = "minniekwok223@domain.com";
    $mail->Password = "123456"; 
    $mail->From = "minniekwok223@domain.com";
    $mail->FromName = "minnie kwok"; 
    $mail->Subject = $subject; 
    $mail->Body = $body; 
    $mail->IsHTML(true); 
    $mail->AddAddress($to);
?>

谁总是去hotmail垃圾文件夹谁有人可以帮忙？