title: Cannot redeclare class PHPMailer
body: <p>This is confusing because I've checked other answers and applied them, but I still keep getting this fatal error.</p>
  
  <p>I'm using phpmailer in wordpress and have this code:</p>
  
  <pre><code>if (!class_exists('PHPMailer')) {
      require_once(ABSPATH . 'wp-content/uploads/phpmailer/_lib/class.phpmailer.php');
  }
  </code></pre>
  
  <p>The page doesn't load, however, and I get the error:</p>
  
  <blockquote>
    <p>PHP Fatal error:  Cannot redeclare class PHPMailer in</p>
  </blockquote>
  
  <p>(I also tried class_exists('PHPMailer', false)) but that also produced the same error.)</p>
  
  <p>As far as I can see, by checking the class does not exist and then using require_once I shouldn't have this problem.</p>
  
  <p>But I do...</p>
  
  <p>Any help appreciated.</p>