code: @Test public void LBCLASSIC_104() throws Exception {
    String subject="LBCLASSIC_104";
    buildSMTPAppender(subject,SYNCHRONOUS);
    smtpAppender.setAsynchronousSending(false);
    smtpAppender.setLayout(buildPatternLayout(DEFAULT_PATTERN));
    smtpAppender.start();
    logger.addAppender(smtpAppender);
    MDC.put("key","val");
    logger.debug("LBCLASSIC_104");
    MDC.clear();
    logger.error("en error",new Exception("test"));
    MimeMultipart mp=verifyAndExtractMimeMultipart(subject);
    String body=GreenMailUtil.getBody(mp.getBodyPart(0));
    assertTrue(body.startsWith(HEADER.trim()));
    System.out.println(body);
    assertTrue(body.contains("key=val"));
    assertTrue(body.endsWith(FOOTER.trim()));
  }
  