props.setProperty(FessEnv.MAIL_SMTP_SERVER_MAIN_HOST_AND_PORT, "smtp-relay.example.com:465");
                props.setProperty(FessEnv.MAIL_SUBJECT_TEST_PREFIX, "[テスト環境]");
                props.setProperty(FessEnv.MAIL_RETURN_PATH, "******@****.***");
                return props;
            }
        };

        assertEquals("smtp-relay.example.com:465", specialMailEnv.getMailSmtpServerMainHostAndPort());

     */
    boolean isMailSendMock();

    /**
     * Get the value for the key 'mail.smtp.server.main.host.and.port'. <br>
     * The value is, e.g. localhost:25 <br>
     * comment: SMTP server settings for main: host:port
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */

        }
    }

    // Test with different hostnames
    @Test
    public void test_differentHostnames() {
        String[] hostnames = { "smtp.gmail.com", "mail.example.com", "localhost", "192.168.1.1" };

        for (String hostname : hostnames) {
            ComponentUtil.setFessConfig(new FessConfig.SimpleImpl() {