Email handling in Google App Engine for Java

package com.yourappname;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.internet.MimeMessage;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings("serial")
public class MailHandlerServlet extends HttpServlet {
    public void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws IOException {
        try {
            MimeMessage message = MimeUtils.createMimeMessage(req);

            if (processMessage(message)) {
                Debug.log("Incoming email handled");
            } else {
                Debug.log("Failed to handle incoming email");
            }
        } catch (MessagingException e) {
            Debug.log("MessagingException: " + e);
            e.printStackTrace();
        }
    }

    private boolean processMessage(MimeMessage message) {
        String date = getMessageDate(message);
        String from = "unknown";

        try {
            from = message.getFrom()[0].toString();
            Object content = MimeUtils.getContent(message);

            if (message.getContentType().startsWith("text/plain")) {
                processMail(from, date, (String) content);
                return true;
            } else if (content instanceof Multipart) {
                Multipart mp = (Multipart) content;
                for (int i = 0; i < mp.getCount(); i++) {
                    if (handlePart(from, date, mp.getBodyPart(i))) {
                        return true;
                    }
                }
                return false;
            } else {
                Debug.log("Unable to process message content - unknown content type");
            }
        } catch (IOException e) {
            Debug.log("Exception handling incoming email " + e);
        } catch (MessagingException e) {
            Debug.log("Exception handling incoming email " + e);
        } catch (Exception e) {
            Debug.log("Exception handling incoming email " + e);
        }

        return false;
    }

    private boolean handlePart(String from, String date, BodyPart part)
            throws MessagingException, IOException {
        if (part.getContentType().startsWith("text/plain")
                || part.getContentType().startsWith("text/html")) {
            processMail(from, date, (String) part.getContent());
            return true;
        } else {
            if (part.getContent() instanceof Multipart) {
                Multipart mp = (Multipart) part.getContent();
                Debug.log("Handling a multipart sub-message with " + mp.getCount() + " sub-parts");
                for (int i = 0; i < mp.getCount(); i++) {
                    if (handlePart(from, date, mp.getBodyPart(i))) {
                        return true;
                    }
                }
                Debug.log("No text or HTML part in the multipart mime sub-message");
            }
            return false;
        }
    }

    private String getMessageDate(Message message) {
        Date when = null;
        try {
            when = message.getReceivedDate();
            if (when == null) {
                when = message.getSentDate();
            }
            if (when == null) {
                return null;
            }
        } catch (MessagingException e) {
            Debug.log("Cannot get message date: " + e);
            e.printStackTrace();
            return null;
        }

        DateFormat format = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss");
        return format.format(when);
    }
}