if (notification == null) {
            failedSendingUserNotification(con, daos, it, envelope, notification);
            return;
        }
        UserEx sender = UserDAOFacade.getUserEx(con, daos, notification.getUserId());
        if (sender == null) {
            Logger.warn("sendTwitterMessage : sender is null.");
            failedSendingUserNotification(con, daos, it, envelope, notification);
            return;
        }
        UserTwitterLink twitterLinkage = sender.getTwitterLinkage();
        if (twitterLinkage == null || !twitterLinkage.isAuthorized()) {
            Logger.warn("sendTwitterMessage : envelope id " + envelope.getId() + " could not be sent : No access token");
            failedSendingUserNotification(con, daos, it, envelope, notification);
            return;
        }