[java] Could not connect to SMTP host: smtp.gmail.com, port: 465, response: -1

while sending mail I am getting this error

java.lang.RuntimeException: javax.mail.SendFailedException: Sending failed; nested exception is: class javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465, response: -1

my code is:

Properties props = new Properties();
props.put("mail.smtp.host", "smtp.gmail.com");
props.put("mail.smtp.starttls.enable","true");
props.put("mail.smtp.socketFactory.port", "465");
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.port", "465");

Session session = Session.getDefaultInstance(props,
        new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication("email","password");
                }
        });

try {

        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress("email"));
        message.setRecipients(Message.RecipientType.TO,
                        InternetAddress.parse(this.to));
        message.setSubject("Testing");
        message.setText("Hey, this is the testing email.");



        Transport.send(message);

Any help would be appreciated.

Thanks in Advance.

In my case it was Avast Antivirus interfering with the connection. Actions to disable this feature: Avast -> Settings-> Components -> Mail Shield (Customize) -> SSL scanning -> uncheck "Scan SSL connections".

I have been experiencing this issue when debugging using NetBeans, even executing the actual jar file. Antivirus would block sending email. You should temporarily disable your antivirus during debugging or exclude NetBeans and the actual jar file from being scanned. In my case, I'm using Avast.

See this link on how to Exclude : How to Add File/Website Exception into avast! Antivirus 2014

It works for me.

Port 465 is for "smtp over SSL".

http://javamail.kenai.com/nonav/javadocs/com/sun/mail/smtp/package-summary.html

[...] For example, use
    props.put("mail.smtp.port", "888");
to set the mail.smtp.port property, which is of type int.

Note that if you're using the "smtps" protocol to access SMTP over SSL, 
all the properties would be named "mail.smtps.*"

What i did was i commented out the

props.put("mail.smtp.starttls.enable","true"); 

Because apparently for G-mail you did not need it. Then if you haven't already done this you need to create an app password in G-mail for your program. I did that and it worked perfectly. Here this link will show you how: https://support.google.com/accounts/answer/185833.

You need to tell it that you are using SSL:

props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");

In case you miss anything, here is working code:

String  d_email = "[email protected]",
            d_uname = "Name",
            d_password = "urpassword",
            d_host = "smtp.gmail.com",
            d_port  = "465",
            m_to = "[email protected]",
            m_subject = "Indoors Readable File: " + params[0].getName(),
            m_text = "This message is from Indoor Positioning App. Required file(s) are attached.";
    Properties props = new Properties();
    props.put("mail.smtp.user", d_email);
    props.put("mail.smtp.host", d_host);
    props.put("mail.smtp.port", d_port);
    props.put("mail.smtp.starttls.enable","true");
    props.put("mail.smtp.debug", "true");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.socketFactory.port", d_port);
    props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.socketFactory.fallback", "false");

    SMTPAuthenticator auth = new SMTPAuthenticator();
    Session session = Session.getInstance(props, auth);
    session.setDebug(true);

    MimeMessage msg = new MimeMessage(session);
    try {
        msg.setSubject(m_subject);
        msg.setFrom(new InternetAddress(d_email));
        msg.addRecipient(Message.RecipientType.TO, new InternetAddress(m_to));

Transport transport = session.getTransport("smtps");
            transport.connect(d_host, Integer.valueOf(d_port), d_uname, d_password);
            transport.sendMessage(msg, msg.getAllRecipients());
            transport.close();

        } catch (AddressException e) {
            e.printStackTrace();
            return false;
        } catch (MessagingException e) {
            e.printStackTrace();
            return false;
        }