title: How to add content to a Mailchimp email using API V3.0
body: <p>I've successfully used the Mailchimp V3.0 API to create a new campaign and have attempted to subsequently add content to that campaign/email but I can't get it to add the content. Following is the (test) code:</p>
  
  <pre><code>$email_test_message = "Testing API v3.0";
  $Content_options = array(
      'plain_text' =&gt; $email_test_message
                          );    
  $json_content = json_encode($Content_options);
  $auth = base64_encode('PRCadmin:' . $MAILCHIMP_API_KEY );
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $MAILCHIMP_URL_API_V3 . '/campaigns/' .   $campaign_id . '/content');
  curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json',
          'Authorization: Basic ' . $auth));
  curl_setopt($ch, CURLOPT_USERAGENT, 'PHP-MCAPI/3.0');
  curl_setopt($ch, CURLOPT_TIMEOUT, 30);
  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT');
  curl_setopt($ch, CURLOPT_POST, true);    
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  curl_setopt($ch, CURLOPT_POSTFIELDS, $json_content); 
  $retval = curl_exec($ch);             
  $json = json_decode($retval);          
  curl_close($ch);                       
  </code></pre>