Sending email using JSP

Well offhand I would say there is an authentication issue when trying to connect. You are not providing any username or password, unless your exchange server doesn't require username and password.

UPDATE: If using JDK 7 see the following post, it resolved this issue:

Defect - JDK7 Permission Denied with Sockets when using VPN

"More digging around and it seems the VPN client has IPv6 disabled which is causing issues with JDK7. If I use the following flag -Djava.net.preferIPv4Stack=true I no longer see the errors. Is this workaround expected or is this an issue?"

public class MailTest {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws MessagingException {
        String host = "smtp.gmail.com";
        String to = "[email protected]";
        String from = "[email protected]";
        String subject = "test";
        String messageText = "body test";

        Properties props = System.getProperties();
        props.put("mail.host", host);
        props.put("mail.transport.protocol", "smtp");
        props.put("mail.smtp.port", "25");

        // If using authentication, otherwise comment out
        props.put("mail.smtp.auth", "true");

        // Gmail requires TLS, your server may not
        props.put("mail.smtp.starttls.enable", "true");

        Session mailSession = Session.getDefaultInstance(props, null);

        Message msg = new MimeMessage(mailSession);
        msg.setFrom(new InternetAddress(from));
        InternetAddress[] address = {new InternetAddress(to)};
        msg.setRecipients(Message.RecipientType.TO, address);
        msg.setSubject(subject);
        msg.setSentDate(new Date());
        msg.setText(messageText);

        Transport transport = mailSession.getTransport("smtp");

        //connect with authentication
        //transport.connect(host,"myUsername" , "myPassword");

        //connect without authentication
        transport.connect();
        transport.sendMessage(msg, address);

        transport.close();

        System.out.println("Mail was sent to " + to);
        System.out.println(" from " + from);
        System.out.println(" using host " + host + ".");

    }
}

If you do not want to change the preferred IP stack to IPv4, an alternative solution might be to use the IPv6 address for the host in stead of the DHCP name, e.g.:

String host = "fe80::b84d:1ed2:5329:de87%10";

The reason of the error is indeed that IPv6 is defaulted on Windows starting from JDK 7. When you attempt to connect to an IPv4 address then under the covers it will use an IPv4-mapped IPv6 address (see this blog from the Oracle website). But normally this should be no problem, if your exchange server supports IPv6. However, I ran in a similar issue when sending a mail from Java code through an MS Exchange 2010 Server after switching to JDK 7. The strange thing is that according to this link on MS Technet it supports IPv6. Since I did not want to default the IP stack of our complete application to IPv4, the accepted solution by setting the flag -Djava.net.preferIPv4Stack=true when starting the application was not an option. Thus changing the host name to a valid IPv6 was a better solution in my case. It's not 100% clear to me why this works and not the DHCP name.