void buildSMTPAppender(String subject, boolean synchronicity) throws Exception {
   smtpAppender = new SMTPAppender();
   smtpAppender.setContext(loggerContext);
   smtpAppender.setName("smtp");
   smtpAppender.setFrom("*****@*****.**");
   smtpAppender.setSMTPHost("localhost");
   smtpAppender.setSMTPPort(port);
   smtpAppender.setSubject(subject);
   smtpAppender.addTo("*****@*****.**");
   smtpAppender.setAsynchronousSending(synchronicity);
 }
 private void buildSMTPAppender(int port, boolean synchronicity) throws Exception {
   smtpAppender = new SMTPAppender();
   smtpAppender.setContext(lc);
   smtpAppender.setName("smtp");
   smtpAppender.setFrom("*****@*****.**");
   smtpAppender.setSMTPHost("localhost");
   smtpAppender.setSMTPPort(port);
   smtpAppender.setSubject(TEST_SUBJECT);
   smtpAppender.addTo("*****@*****.**");
   smtpAppender.setAsynchronousSending(synchronicity);
   // smtpAppender.start();
 }
  @Test
  public void testMultipleTo() throws Exception {
    buildSMTPAppender(smtpServer.getSmtp().getPort(), SYNCHRONOUS);
    smtpAppender.setLayout(buildPatternLayout(lc, DEFAULT_PATTERN));
    smtpAppender.addTo("Test <*****@*****.**>, [email protected]");
    smtpAppender.start();
    logger.addAppender(smtpAppender);
    logger.debug("hello");
    logger.error("an error", new Exception("an exception"));

    waitUntilEmailIsReceived(smtpServer, 3);
    MimeMessage[] mma = smtpServer.getReceivedMessages();
    assertNotNull(mma);
    assertEquals(3, mma.length);
  }
 // this test fails intermittently on Jenkins.
 @Test
 public void testMultipleTo() throws Exception {
   buildSMTPAppender("testMultipleTo", SYNCHRONOUS);
   smtpAppender.setLayout(buildPatternLayout(DEFAULT_PATTERN));
   // buildSMTPAppender() already added one destination address
   smtpAppender.addTo("Test <*****@*****.**>, [email protected]");
   smtpAppender.start();
   logger.addAppender(smtpAppender);
   logger.debug("testMultipleTo hello");
   logger.error("testMultipleTo en error", new Exception("an exception"));
   Thread.yield();
   int expectedEmailCount = 3;
   waitForServerToReceiveEmails(expectedEmailCount);
   MimeMessage[] mma = greenMailServer.getReceivedMessages();
   assertNotNull(mma);
   assertEquals(expectedEmailCount, mma.length);
 }