public static function donation_button_mailchimp_handler($posted)
 {
     if (!isset($posted) || empty($posted)) {
         return;
     }
     $debug = get_option('log_enable_mailchimp') == 'yes' ? 'yes' : 'no';
     if ('yes' == $debug) {
         $log = new Donation_Button_Logger();
     }
     $apikey = get_option('mailchimp_api_key');
     $listId = get_option('mailchimp_lists');
     $first_name = isset($posted['first_name']) ? $posted['first_name'] : '';
     $last_name = isset($posted['last_name']) ? $posted['last_name'] : '';
     $payer_email = isset($posted['payer_email']) ? $posted['payer_email'] : $posted['receiver_email'];
     $merge_vars = array('FNAME' => $first_name, 'LNAME' => $last_name);
     if (isset($apikey) && !empty($apikey)) {
         if (isset($listId) && !empty($listId)) {
             include_once 'class-donation-button-mcapi.php';
             $api = new Donation_Button_MailChimp_MCAPI($apikey);
             try {
                 $retval = $api->listSubscribe($listId, $payer_email, $merge_vars, $email_type = 'html');
                 if ('yes' == $debug) {
                     if ("true" == $retval) {
                         $log->add('MailChimp', $payer_email . ' Successfully Add Contact in Mailchimp');
                     } else {
                         $log->add('MailChimp', $payer_email . ' in Mailchimp');
                     }
                 }
             } catch (Mailchimp_Error $e) {
                 if ('yes' == $debug) {
                     $log->add('MailChimp', print_r($e, true));
                 }
             }
         } else {
             if ('yes' == $debug) {
                 $log->add('MailChimp', 'MailChimp List Id is Empty.');
             }
         }
     } else {
         if ('yes' == $debug) {
             $log->add('MailChimp', 'MailChimp Api Key is Empty.');
         }
     }
 }