폼메일 발송시 보낸사람 주소가 root@로 나오는 오류

</p>

<p><?php

//받는사람

  $recipient = "abc@dfg.com";

//제목 처리

  $subject = '=?UTF-8?B?'.base64_encode("[문의]".$_GET['senduser']).'?=';

//메일주소

  $mail_from = '=?UTF-8?B?'.base64_encode($_GET['email']).'?=';</p>

<p>//메일내용

  $mail_body = "<table width='600' border='0' cellpadding='0' cellspacing='1' bgcolor='#CCCCCC'></p>

<p>          <tr> 

          <td width='100' height='30' align='center' bgcolor='#eeeeee'>이름</td>

          <td width='400' bgcolor='#FFFFFF'>". $_GET['senduser']."</td></tr>".        

          

       " <tr> 

          <td width='100' height='30' align='center' bgcolor='#eeeeee'>연락처</td>

          <td width='400' bgcolor='#FFFFFF'>". $_GET['phone']."</td></tr>".    

          

       " <tr> 

          <td width='100' height='30' align='center' bgcolor='#eeeeee'>이메일</td>

          <td width='400' bgcolor='#FFFFFF'>". $_GET['email']."</td></tr>".    

      

       " <tr> 

          <td width='100' height='30' align='center' bgcolor='#eeeeee'>상담희망 시간</td>

          <td width='400' bgcolor='#FFFFFF'>". $_GET['check']."</td></tr>".    

      

       " <tr> 

          <td width='100' height='30' align='center' bgcolor='#eeeeee'>문의사항</td>

          <td width='400' bgcolor='#FFFFFF'>". $_GET['body']."</td></tr>".    

          

      "</table>";</p>

<p> 

//메일 발송처리</p>

<p>  $header = "From:$subject\n";

  $header = "Content-Type: text/html;charset=UTF-8";

  $header .= "From : $mail_from <".$mail_from.">\n"; </p>

<p>$ext = "-f ".$_GET['email'];

$email = mail($recipient, $subject, $mail_body, $header, $ext);</p>

<p>

  if (!$email)

    echo "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" /> <script>

         window.alert('상담 신청에 실패하였습니다.');

         history.go(-1);

         </script>";

  else

    echo "         <script>

         window.alert('상담 신청이 정상적으로 처리되었습니다.');

         history.go(-1);

         </script>";

?></p>

<p>