How to use

getCause

method

in

javax.mail.MessagingException

@Override
public Throwable getCause() {
 return exception.getCause();
}

if (e.getCause() instanceof NullPointerException) {
  failed.getAndIncrement();

  /**
   * @see MessageBodyWriter#writeTo(Object, Class, Type, Annotation[],
   *      MediaType, MultivaluedMap, OutputStream)
   */
  public void writeTo(Multipart multipart, Class<?> type, Type genericType,
      Annotation[] annotations, MediaType mediaType,
      MultivaluedMap<String, Object> httpHeaders,
      OutputStream entityStream) throws IOException {
    try {
      multipart.writeTo(entityStream);
    } catch (MessagingException e) {
      if (e.getCause() instanceof IOException) {
        throw (IOException) e.getCause();
      }
      final IOException ioExc = new IOException(
          "Could not serialize the Multipart");
      ioExc.initCause(e);
      throw ioExc;
    }
  }
}

/**
 * @see MessageBodyReader#readFrom(Class, Type, Annotation[], MediaType,
 *      MultivaluedMap, InputStream)
 */
public Multipart readFrom(Class<Multipart> type, Type genericType,
    Annotation[] annotations, MediaType mediaType,
    MultivaluedMap<String, String> httpResponseHeaders,
    InputStream entityStream) throws IOException {
  final String contentType = "multipart/form-data";
  final DataSource ds = new ByteArrayDataSource(entityStream, contentType);
  try {
    return new MimeMultipart(ds);
  } catch (MessagingException e) {
    if (e.getCause() instanceof IOException) {
      throw (IOException) e.getCause();
    }
    final IOException ioExc = new IOException(
        "Could not deserialize the data to a Multipart");
    ioExc.initCause(e);
    throw ioExc;
  }
}

 /**
  * Generates output for requests that target media resources.
  */
 public void generate(OutputStream contentStream, OutputProperties request, 
    MediaMultipart source) throws IOException {

  OutputProperties prevProperties = null;
  try {
   prevProperties =
     GDataContentHandler.setThreadOutputProperties(request);
   source.writeTo(contentStream);
  } catch (MessagingException me) {
   
   // Unwrap basic I/O errors 
   Throwable t = me.getCause();
   if (t instanceof IOException) {
    throw (IOException) t;
   }
   
   // Wrap others based upon an invalid input entry
   IOException ioe = new IOException("Invalid multipart content");
   ioe.initCause(new InvalidEntryException("Invalid media entry", me));
   throw ioe;
  } finally {
   GDataContentHandler.setThreadOutputProperties(prevProperties);
  }
 }
}

 /**
  * Generates output for requests that target media resources.
  */
 public void generate(OutputStream contentStream, OutputProperties request, 
    MediaMultipart source) throws IOException {

  OutputProperties prevProperties = null;
  try {
   prevProperties =
     GDataContentHandler.setThreadOutputProperties(request);
   source.writeTo(contentStream);
  } catch (MessagingException me) {
   
   // Unwrap basic I/O errors 
   Throwable t = me.getCause();
   if (t instanceof IOException) {
    throw (IOException) t;
   }
   
   // Wrap others based upon an invalid input entry
   IOException ioe = new IOException("Invalid multipart content");
   ioe.initCause(new InvalidEntryException("Invalid media entry", me));
   throw ioe;
  } finally {
   GDataContentHandler.setThreadOutputProperties(prevProperties);
  }
 }
}

} catch (MessagingException e) {
  String cause = "";
  if ((e instanceof SendFailedException) && (e.getCause() instanceof SendFailedException)) {
    cause = " - Cause: " + e.getCause().getMessage();

private ExecutionResult doDeliver(Mail mail, InternetAddress[] addr, Iterator<HostAddress> targetServers) throws MessagingException {
  MessagingException lastError = null;
  while (targetServers.hasNext()) {
    try {
      return mailDelivrerToHost.tryDeliveryToHost(mail, addr, targetServers.next());
    } catch (SendFailedException sfe) {
      lastError = handleSendFailExceptionOnMxIteration(mail, sfe);
    } catch (MessagingException me) {
      lastError = handleMessagingException(mail, me);
      if (configuration.isDebug()) {
        LOGGER.debug(me.getMessage(), me.getCause());
      } else {
        LOGGER.info(me.getMessage());
      }
    }
  }
  // If we encountered an exception while looping through,
  // throw the last MessagingException we caught. We only
  // do this if we were unable to send the message to any
  // server. If sending eventually succeeded, we exit
  // deliver() though the return at the end of the try
  // block.
  if (lastError != null) {
    throw lastError;
  }
  return ExecutionResult.temporaryFailure();
}

  e.printStackTrace();                        
} catch (MessagingException e) {
  logger.warn(new MailerException("Unable to sent email to "+mailerConfigurator.getRecipients()+": "+e.getMessage()), e.getCause());
  e.printStackTrace();
} catch (IOException e) {

if (e.getCause() != null)
  cause = ", caused by: " + e.getCause().toString();

if(ex.getCause() instanceof SocketTimeoutException) {
  throw new CREIOException(ex.getCause().getMessage(), t, ex);

if (WebExceptionHelper.isServerNotReachableConnection (ex.getCause ()))
 aExceptionToBeRemembered = new MailSendException ("Failed to connect to mail server: " +
                          ex.getCause ().getMessage ());
else
 aExceptionToBeRemembered = new MailSendException ("Mail server connection failed", ex);