sending java mail from with in a proxy server

I am trying to send Email using java mail API from with in a proxy server. The code is as follows: ``` import java.security.Security; import java.util.Date; import java.util.Properties; import javax.mail.Authenticator; import javax.mail.Message; import javax.mail.MessagingException; import javax.mail.PasswordAuthentication; import javax.mail.Session; import javax.mail.Transport; import javax.mail.internet.AddressException; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; public class GmailSender { public static void main(String[] args) throws AddressException, MessagingException { Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider()); final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory"; // Get a Properties object Properties props = System.getProperties(); props.setProperty("proxySet","true"); props.setProperty("socksProxyHost","192.168.1.103"); props.setProperty("socksProxyPort","3128"); props.setProperty("mail.smtp.host", "smtp.gmail.com"); props.setProperty("mail.smtp.socketFactory.class", SSL_FACTORY); props.setProperty("mail.smtp.socketFactory.fallback", "false"); props.setProperty("mail.smtp.port", "465"); props.setProperty("mail.smtp.socketFactory.port", "465"); props.put("mail.smtp.auth", "true"); props.put("mail.debug", "true"); props.put("mail.store.protocol", "pop3"); props.put("mail.transport.protocol", "smtp"); final String username = "proxy_userName"; final String password = "proxy_password"; Session session = Session.getDefaultInstance(props, new Authenticator(){ protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(username, password); }}); // -- Create a new message -- Message msg = new MimeMessage(session); // -- Set the FROM and TO fields -- msg.setFrom(new InternetAddress("xxxxxxx@gmail.com")); msg.setRecipients(Message.RecipientType.TO, InternetAddress.parse("xxxxxxx@gmail.com",false)); msg.setSubject("Hello"); msg.setText("How are you"); msg.setSentDate(new Date()); Transport.send(msg); System.out.println("Message sent."); } } ``` when I run this code following message is displayed. ``` DEBUG: JavaMail version 1.4.3 DEBUG: successfully loaded resource: /META-INF/javamail.default.providers DEBUG: Tables of loaded providers DEBUG: Providers Listed By Class Name: {com.sun.mail.smtp.SMTPSSLTransport=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.S MTPSSLTransport,Sun Microsystems, Inc], com.sun.mail.smtp.SMTPTransport=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTr ansport,Sun Microsystems, Inc], com.sun.mail.imap.IMAPSSLStore=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLSto re,Sun Microsystems, Inc], com.sun.mail.pop3.POP3SSLStore=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLSto re,Sun Microsystems, Inc], com.sun.mail.imap.IMAPStore=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3Store=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc]} DEBUG: Providers Listed By Protocol: {imaps=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Sun Microsystems, Inc], imap=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], smtps=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc], pop3=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc], pop3s=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc], smtp=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]} DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc] DEBUG SMTP: useEhlo true, useAuth true DEBUG SMTP: useEhlo true, useAuth true DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 465, isSSL false Exception in thread "main" javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465; nested exception is: java.io.IOException: Couldn't connect using unknown socket factory to host, port: smtp.gmail.com, -1; Exception: java.lang.ClassNotFoundException: false at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1706) at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:525) at javax.mail.Service.connect(Service.java:313) at javax.mail.Service.connect(Service.java:172) at javax.mail.Service.connect(Service.java:121) at javax.mail.Transport.send0(Transport.java:190) at javax.mail.Transport.send(Transport.java:120) at GmailSender.main(GmailSender.java:57) Caused by: java.io.IOException: Couldn't connect using unknown socket factory to host, port: smtp.gmail.com, -1; Exception: java.lang.ClassNotFoundException: false at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:216) at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1672) ... 7 more Caused by: java.lang.ClassNotFoundException: false at java.net.URLClassLoader$1.run(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at com.sun.mail.util.SocketFetcher.getSocketFactory(SocketFetcher.java:322) at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:187) ... 8 more ``` May be the problem is due to the presence of the proxy server. However I could send the mails by logging in to gmail using browser from with in same proxy server. Kindly suggest as why the programmatic method is failing and the browser method is working. I would be thankful for any help.