code: protected function throttleDataWrite()
      {
          $return = true;
          $this->throttleDataGarbageCollection();
          if ($this->cfg['emailThrottleWrite'] && \is_callable($this->cfg['emailThrottleWrite'])) {
              $return = \call_user_func($this->cfg[''], $this->throttleData);
              if (!$return) {
                  \error_log('ErrorEmailer: emailThrottleWrite() returned false');
              }
          } elseif ($this->cfg['emailThrottleFile']) {
              $wrote = $this->fileWrite($this->cfg['emailThrottleFile'], \json_encode($this->throttleData, JSON_PRETTY_PRINT));
              if (!$wrote) {
                  $return = false;
                  \error_log('Unable to write to '.$this->cfg['emailThrottleFile']);
              }
          }
          return $return;
      }
docs: Export/Save/Write throttle data
  
  Uses cfg[emailThrottleWrite] callable if set, otherwise, writes to cfg['emailThrottleFile']
  
  @return boolean