check if blacklisted_domains is empty

	public function isBlacklistedEmail(string $email): bool {

		// Get the blacklisted domains from configuration

		$blacklistedDomainsInJson = $this->config->getAppValue(Application::APP_ID, 'blacklisted_domains');

		if (empty($blacklistedDomainsInJson)) {

			return false;

		}

		$blacklistedDomains = json_decode($blacklistedDomainsInJson, true);

		if (empty($blacklistedDomains)) {

			return false;

		}

		// Split the email address into parts using explode

		$emailParts = explode('@', $email);