PHP Mail Form

Code:
<html>
<body>

<?php
if (isset($_REQUEST['email']))

  {

  $email = $_REQUEST['email'] ;
  $subject = $_REQUEST['subject'] ;
  $message = $_REQUEST['message'] ;
  mail("", $subject,
  $message, "From:" . $email);
  
  }
else

  {
  echo "<form method='post' action=''>
  Email: <input name='email' type='text' /><br />
  Subject: <input name='subject' type='text' /><br />
  Message:<br />
  <textarea name='message' rows='15' cols='40'>
  </textarea><br />
  <input type='submit' />
  </form>";
  }
?>

</body>
</html>