title: Blocking referrer spam by domain - is a 403 response efficient
body: <p>I'm about to implement the following code to block some referrer spam a client has been receiving. </p>
  
  <p>Is a 403 the most efficient way (I believe the header size is 0 bytes, or at least small) of redirecting the request, or are there other options I should consider?</p>
  
  <pre><code>RewriteEngine on
  # Options +FollowSymlinks
  RewriteCond %{HTTP_REFERER} spammer-one\.com [NC,OR]
  RewriteCond %{HTTP_REFERER} spammer-two\.com
  RewriteCond %{HTTP_REFERER} spammer-three\.com
  RewriteRule .* - [F]
  </code></pre>
  
  <p>The source of concern is that their site is receiving a huge volume of traffic from a number of spam domains, server load could be a factor.</p>