code: @Override
      public void afterPropertiesSet() throws Exception {
          greenMail = new GreenMail(createServerSetup());
          if (null != users) {
              for (String user : users) {
                  int posColon = user.indexOf(':');
                  int posAt = user.indexOf('@');
                  String login = user.substring(0, posColon);
                  String pwd = user.substring(posColon + 1, posAt);
                  String domain = user.substring(posAt + 1);
                  if (log.isDebugEnabled()) {
                      log.debug("Adding user {}:{}@{}" ,login, pwd, domain);
                  }
                  greenMail.setUser(login + '@' + domain, login, pwd);
              }
          }
          if (autostart) {
              greenMail.start();
              started = true;
          }
      }
docs: Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied
  BeanFactoryAware and ApplicationContextAware). <p>This method allows the bean instance to
  perform initialization only possible when all bean properties have been set and to throw an
  exception in the event of misconfiguration.
  
  @throws Exception in the event of misconfiguration (such as failure to set an essential
  property) or if initialization fails.