Mailgun\Messages\MessageBuilder::setClickTracking PHP Method

    public function setClickTracking($enabled)
    {
        if (filter_var($enabled, FILTER_VALIDATE_BOOLEAN)) {
            $enabled = 'yes';
        } elseif ($enabled == 'html') {
            $enabled = 'html';
        } else {
            $enabled = 'no';
        }
        $this->message['o:tracking-clicks'] = $enabled;
        return $this->message['o:tracking-clicks'];
    }

 /**
  * Toggles clicks tracking on a per-message basis.
  * This setting has a higher priority than the domain-level setting.
  * Pass `true`, `false` or 'html' or 'htmlonly'.
  *
  * @param bool|string $value
  *
  * @return \Bogardo\Mailgun\Mail\Message
  */
 public function trackClicks($value)
 {
     $value = $value === 'htmlonly' ? 'html' : $value;
     $this->messageBuilder->setClickTracking($value);
     return $this;
 }