code: public function canCreate(ContainerInterface $container, $requestedName): bool
      {
          $parts = explode('.', $requestedName);
          if (count($parts) !== 3) {
              return false;
          }
  
          if ($parts[0] !== self::ACMAILER_PART || $parts[1] !== static::MAIL_SERVICE_PART) {
              return false;
          }
  
          $specificServiceName = $parts[2];
          $config = $container->get('config')['acmailer_options']['mail_services'] ?? [];
          return array_key_exists($specificServiceName, $config);
      }
docs: Can the factory create an instance for the service?
  
  @param  ContainerInterface $container
  @param  string $requestedName
  @return bool
  @throws ContainerExceptionInterface