phpmailer を使用して大量のメールを送信するのに問題がありましたが、単一のメールでは問題ありません。
ここに私のコードがあります:
$result = mysql_query("select * from $to",$conn) or die("list 
            selected  ($to) does not exist ".mysql_error());
while ($row = mysql_fetch_array($result))
{           
    $email[] = $row['email'];           
    $student[] = $row['name'];
}
foreach ($email as $val => $uemail) {
    $email = $uemail;
    $students= $student[$val] ;
    require("class.phpmailer.php");
        $mail = new PHPMailer(true); 
    try {
           $mail->AddReplyTo('info@bratim.com', 'My Name');
           $mail->AddAddress("$email", "$student");
           $mail->SetFrom('info@me.com', 'MyName');
           $mail->AddReplyTo('info@me.com', 'My nameg');
           $mail->Subject = "$sub";
           $mail->MsgHTML("Dear $student<br> $msg <br>
             <img src=\"$path\"> <p>
             $host_upper
            ______________________________________________________
            THIS IS AN AUTOMATED RESPONSE. 
            ***DO NOT RESPOND TO THIS EMAIL****
             ");
            $mail->AddAttachment("$path2");      // attachment
          $mail->Send();
          echo "Message Sent OK to $email  </p>\n";
    } catch (phpmailerException $e) {
        echo $e->errorMessage(); //Pretty error messages from PHPMailer
    } catch (Exception $e) {
        echo $e->getMessage(); //Boring error messages from anything else!
    } 
}
任意のヘルプ、提案をいただければ幸いです。