JavaMail Gmail Exception when reading mails

Question

I am using JavaMail for reading messages in a gmail account.
My general problem is validationException. My code is the following.
public class MessagesReader {
     public static String usage = "Usage: java gmailTest user password subject";
     public static void main(String[] args) {
          String username = "username";
          String password = "password";
          Properties pop3Props = new Properties();
          Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider());
          pop3Props.setProperty("mail.pop3.user", username);
          pop3Props.setProperty("mail.pop3.passwd", password);
          pop3Props.setProperty("mail.pop3.ssl", "true");
          pop3Props.setProperty("mail.pop3.host", "pop.gmail.com");
          try {
               checkForMessage(pop3Props, null);
          } catch (Exception e) {
               e.printStackTrace();
     public static void checkForMessage(Properties props, String msgSubject)
               throws NoSuchProviderException, MessagingException {
          Session session = null;
          Store store = null;
          String user = ((props.getProperty("mail.pop3.user") != null) ? props
                    .getProperty("mail.pop3.user") : props.getProperty("mail.user"));
          String passwd = ((props.getProperty("mail.pop3.passwd") != null) ? props
                    .getProperty("mail.pop3.passwd")
                    : props.getProperty("mail.passwd"));
          String host = ((props.getProperty("mail.pop3.host") != null) ? props
                    .getProperty("mail.pop3.host") : props.getProperty("mail.host"));
          if ((props.getProperty("mail.pop3.ssl") != null)
                    && (props.getProperty("mail.pop3.ssl").equalsIgnoreCase("true"))) {
               String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
               //Replace socket factory
               props.setProperty("mail.pop3.socketFactory.class", SSL_FACTORY);
               // configure the appropriate properties so JavaMail doesn't
               // fall back to an unsecure connection when a secure one fails:
               props.setProperty("mail.pop3.socketFactory.fallback", "false");
               String portStr = ((props.getProperty("mail.pop3.port") != null) ? props
                         .getProperty("mail.pop3.port")
                         : "995");
               //change the default port number to the corresponding port that your protocol's secure version uses;
               //otherwise, you must use a fully qualified address (that includes a port number) in the URL passed
               //to JavaMail (for example, imap://id:[email protected]:993/folder/), or else you get an
               //"unrecognized SSL handshake" exception. You specify these properties like so:
               props.setProperty("mail.pop3.port", portStr);
               props.setProperty("mail.pop3.socketFactory.port", portStr);
               URLName url = new URLName("pop3://" + user + ":" + passwd + "@"
                         + host + ":" + portStr);
               session = Session.getInstance(props, null);
               store = new POP3SSLStore(session, url);
               //Unfortunately, you may realize that the code above throws an SSLException "untrusted server cert chain"
               //if the mail server certificate is not installed locally. In that case, you should obtain a correct,
               //valid certificate for the server and use the keytool utility to add it to a local key storage at
               //<javahome>\jre\lib\security\cacerts.
          } else {
               session = Session.getInstance(props, null);
               store = session.getStore("pop3");
          session.setDebug(true);
          store.connect(host, user, passwd);
          Folder folder = store.getFolder("INBOX");
          folder.open(Folder.READ_WRITE);
          Message[] allMsgs = folder.getMessages();
          for (int i = 0; i < allMsgs.length; i++) {
               System.out.println(allMsgs.getSubject());
          folder.close(true);
          store.close();
When I execute the above code I get the following exception:
[java] DEBUG: setDebug: JavaMail version 1.4ea
     [java] DEBUG POP3: connecting to host "pop.gmail.com", port 995, isSSL true
     [java] javax.mail.MessagingException: Connect failed;
     [java] nested exception is:
     [java] javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: No trusted certificate found
     [java] at com.sun.mail.pop3.POP3Store.protocolConnect(POP3Store.java:148)
     [java] at javax.mail.Service.connect(Service.java:275)
     [java] at javax.mail.Service.connect(Service.java:156)
     [java] at javamail.MessagesReader.checkForMessage(Unknown Source)
     [java] at javamail.MessagesReader.main(Unknown Source)
     [java] Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: No trusted certificate found
     [java] at com.sun.net.ssl.internal.ssl.BaseSSLSocketImpl.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SunJSSE_az.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SunJSSE_az.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SunJSSE_ax.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.j(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.SSLSocketImpl.a(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.AppInputStream.read(DashoA6275)
     [java] at java.io.BufferedInputStream.fill(BufferedInputStream.java:183)
     [java] at java.io.BufferedInputStream.read(BufferedInputStream.java:201)
     [java] at java.io.DataInputStream.readLine(DataInputStream.java:562)
     [java] at com.sun.mail.pop3.Protocol.simpleCommand(Protocol.java:347)
     [java] at com.sun.mail.pop3.Protocol.<init>(Protocol.java:91)
     [java] at com.sun.mail.pop3.POP3Store.getPort(POP3Store.java:201)
     [java] at com.sun.mail.pop3.POP3Store.protocolConnect(POP3Store.java:144)
     [java] ... 4 more
     [java] Caused by: sun.security.validator.ValidatorException: No trusted certificate found
     [java] at sun.security.validator.SimpleValidator.buildTrustedChain(SimpleValidator.java:304)
     [java] at sun.security.validator.SimpleValidator.engineValidate(SimpleValidator.java:107)
     [java] at sun.security.validator.Validator.validate(Validator.java:202)
     [java] at com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(DashoA6275)
     [java] at com.sun.net.ssl.internal.ssl.JsseX509TrustManager.checkServerTrusted(DashoA6275)From all the relative posts I have understood that the problem is associated with an SSL certificate. I have the gmail certificate. Taken from the padlock of the gmail browser page and so I have a gmail.cer.
I know that I have to use a keytool to do something that I have not understand.
Can you please give me some instructions?
Or the forementioned exception has any other solution??
Thanking you in advance

Answer 1

Ok here.. im using this code to read from gmail too....
* MailSender.java
* Created on 14 November 2006, 17:07
* This class is used to send mails to other users
package jmailer;
* @author Abubakar Gurnah
import java.sql.SQLException;
import java.util.*;
import java.io.*;
import java.sql.ResultSet;
import java.text.DateFormatSymbols;
import java.text.SimpleDateFormat;
import javax.mail.*;
import javax.mail.event.*;
import javax.mail.internet.InternetAddress;
/* Monitors given mailbox for new mail */
class MessageRead implements Runnable{
    private String status;
    private String uname;
    private boolean serverStatus=true;
    private String serverConn;
    private int freq;
    private String account;
    private DbConn db;
    private ResultSet rsA;
    private Properties props;
    private Session session;
    private Store store;
    private Folder folder;
     * @param account get the thread account name
     * @param uname logged in user name
     * @param mailServer pop3 mail server
     * @param mailuname pop3 account username e.g [email protected]
     * @param mailPwd pop3 account password
     * @param port pop3 access port
     * @param SSL pop3 support encryption?
     * @param freq the frequency that the server will check for a new message
    public MessageRead(String account,String uname,String mailServer,String mailuname,
            String mailPwd,String port,String SSL,int freq){
        this.uname=uname;
        this.freq=freq;
        this.account=account;
        db=new DbConn();
        rsA=db.executeQuery("SELECT * " +
                "FROM Accounts " +
                "WHERE AccountName='" + uname + "'");
        connectToServer(uname,mailServer,mailuname,
                mailPwd,port,SSL);
     * @param b set the thread on/off
    public void setStatus(boolean b){
        serverStatus=b;
     * @return if the server is on/off
    public boolean getStatus(){
        return serverStatus;
     * @param uname logged in user name
     * @param mailServer pop3 mail server
     * @param mailuname pop3 account username e.g [email protected]
     * @param mailPwd pop3 account password
     * @param port pop3 access port
     * @param SSL pop3 support encryption?
    public void connectToServer(String uname,String mailServer,String mailuname,
            String mailPwd,String port,String SSL){
        serverConn=mailServer+":"+mailuname;
        try {
            if(SSL.equalsIgnoreCase("true")){
                Properties props = System.getProperties();
                props.setProperty( "mail.pop3.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
                props.setProperty( "mail.pop3.socketFactory.fallback", "false");
                props.setProperty("mail.pop3.port", port);
                props.setProperty("mail.pop3.socketFactory.port", port);
                Session session = Session.getInstance(props);
                store = session.getStore("pop3");
            }else{
                props=new Properties();
                props = System.getProperties();
                // Get a Session object
                session = Session.getInstance(props, null);
                store = session.getStore("imap");
            // session.setDebug(true);
            // Get a Store object
            // Connect
            store.connect(mailServer, mailuname, mailPwd);
            // Open a Folder
            folder = store.getFolder("INBOX");
            System.out.println("Opening the inbox folder for " + mailServer);
            if (folder == null || !folder.exists()) {
                //Tray.showBallon("Warning","Invalid folder Name:"+folder.getName(),Tray.WARNING);
                System.exit(1);
            folder.open(Folder.READ_WRITE);
            // Add messageCountListener to listen for new messages
            folder.addMessageCountListener(new MessageCountAdapter() {
                public void messagesAdded(MessageCountEvent ev) {
                    System.out.println("new mail " + serverConn);
                    readMail(ev);
            // Check mail once in "freq" MILLIseconds
        } catch (Exception ex) {
            ex.printStackTrace();
     * Listen for incoming messages
    public void run(){
        try {
            while(serverStatus){
                // sleep for freq milliseconds
                // This is to force the IMAP server to send us
                // EXISTS notifications.
                System.out.println("Reading for change for " + serverConn);
                folder.getMessageCount();
                Thread.sleep(freq);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        } catch (MessagingException ex) {
            ex.printStackTrace();
     * This method is triggered upon receival of the message
     * @param ev Message Object event
    public void readMail(MessageCountEvent ev){
        Message[] msgs = ev.getMessages();
        String from="";
        String subject="";
        String body="";
        status="New Mail";
        // Message retrival part
        for (int i = 0; i < msgs.length; i++) { // for each new entry
            try {
                from=((InternetAddress)msgs.getFrom()[0]).getPersonal(); //get From whom the came from
if (from==null)
from=((InternetAddress)msgs[i].getFrom()[0]).getAddress();
subject=msgs[i].getSubject(); //get the subject of the message
//check message if it contain other parts, such as attachment
Part messagePart = msgs[i];
Object content=messagePart.getContent();
if (content instanceof Multipart){
messagePart=((Multipart)content).getBodyPart(0);
// -- Get the content type --
String contentType=messagePart.getContentType();
//this the mail is plain mail.. or contain some html
if (contentType.startsWith("text/plain")|| contentType.startsWith("text/html")){
//get the mail
BufferedReader reader=new BufferedReader(new InputStreamReader(messagePart.getInputStream()));
//start reading line after line
String b=reader.readLine();
while (b!=null){
b=reader.readLine();
body+=b + "\n";
writingLogs(from + ":" + ((InternetAddress)msgs[i].getFrom()[0]).getAddress(),subject,body);
checkMsg(((InternetAddress)msgs[i].getFrom()[0]).getAddress(),subject,body);
msgs[i].setFlag(Flags.Flag.DELETED, true); //delete the messages
reader.close();
} catch (IOException ioex) {
ioex.printStackTrace();
} catch (MessagingException mex) {
mex.printStackTrace();
* This method is used to write the mail to the log, so as to keep track
* of all the incoming messages...
* @param strFrom from where the mail is originated
* @param strSubject the subject of the message
* @param strBody the body of the message
public void writingLogs(String strFrom,String strSubject,String strBody ){
Date today = new Date();
DateFormatSymbols symbols;
SimpleDateFormat formatter;
symbols = new DateFormatSymbols(new Locale("en","US"));
formatter = new SimpleDateFormat("yyyyMMddHHmmss", symbols);
String result = formatter.format(today);
BufferedWriter bw;
try {
String path=new File(".").getCanonicalPath();
bw = new BufferedWriter(new FileWriter(path+"\\logs\\"+result + ".txt"));
bw.write("From..." + strFrom +"\n");
bw.write("---------------------------------------------------------\n");
bw.write("Subject..."+strSubject+"\n");
bw.write("---------------------------------------------------------\n");
bw.write("Body..."+strBody+"\n");
bw.flush();
bw.close();
} catch (IOException ex) {
ex.printStackTrace();
public void checkMsg(String from,String subject,String body){
String msg="";
ResultSet rsP=db.executeQuery("SELECT * " +
"FROM priority " +
"WHERE uname='" + uname + "'");
try {
boolean fReading=true;
int i=1;
rsP.first();
while(fReading){
int p=checkPriority(rsP.getString("Priority"+(i++)));
if(i>3) {fReading=false;break;}
switch(p){
case 1:
msg=readFrom(from,body);break;
case 2:
msg=readSubject(from,subject,body);break;
case 3:
msg=readBody(from,body);break;
case -1:
fReading=false;break;
} catch (SQLException ex) {
ex.printStackTrace();
public int checkPriority(String p){
if (p.equalsIgnoreCase("From")){
return 1;
}else if(p.equalsIgnoreCase("Subject")){
return 2;
}else if(p.equalsIgnoreCase("Body")){
return 3;
return -1;
private String readBody(String from, String body) {
return null;
private String readSubject(String from, String subject, String body) {
return null;
private String readFrom(String from, String body) {
boolean Matched=false;
String s=from.substring(0,from.indexOf("@"));
ResultSet rsR=db.executeQuery("SELECT * " +
"FROM Rules " +
"WHERE [if]='from' and uname='" + uname + "'");
try {
rsR.first();
do{
Matched=checkPattern(from,rsR.getString("Contains"));
if(Matched){
break;
}while(rsR.next());
MailSender m=new MailSender();
m.send(rsA.getString("smtpmailuname"),
rsA.getString("smtpmailuname"),
rsA.getString("smtpserver"),
rsA.getString("smtpport"),
rsA.getString("smtpmailuname"),
rsR.getString("phoneNo"),
"Server Message",
body
} catch (SQLException ex) {
ex.printStackTrace();
return null;
public boolean checkPattern(String original, String contains){
if(contains.indexOf(original)>0){
return true;
return false;
Let me explain... just consider connectToServer
there is SSL.equalsIgnoreCase("true") which is google.. this is what you want in this if statement... it configure the properties of google... try it..