title: How to avoid automated posting on classifieds?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/111576/when-the-bots-attack">When the bots attack!</a>  </p>
  </blockquote>
  
  
  
  <p>My free classified portal is coded in php. Now am facing sequence of ads which seems to be posted by tools like auto submitter. So I need to detect and avoid these type of ads by an automation which is done in any ways. </p>