MailConnectException while sending mail using java mail api

问题

Trying to send an email using java mail api. And I keep getting MailConnectException. I have tried multiple ways to solve it without success.

Exception is thrown by this statement

transport.connect("smtp.gmail.com", "someone@gmail.com", "myPassword");

Can anyone tell me what I'm doing wrong?

public static void main(String[] args) {
    String host = "smtp.gmail.com";
    String from = "someone@gmail.com";
    Properties props = System.getProperties();
    props.put("mail.smtp.host", host);
    props.put("mail.smtp.user", from);
    props.put("mail.smtp.password", "myPassword");
    props.put("mail.smtp.port", "465"); 
    props.put("mail.smtp.auth", "true");
    try{
        Session session = Session.getDefaultInstance(props, null);
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.addRecipients(Message.RecipientType.TO, "someone@hotmail.com");
        message.setSubject("sending in a group");
        message.setText("Welcome to JavaMail");
        Transport transport = session.getTransport("smtp");
        transport.connect("smtp.gmail.com", "someone@gmail.com", "myPassword");//CAUSES EXCEPTION
        transport.sendMessage(message, message.getAllRecipients());
    }catch(MessagingException e){
        e.printStackTrace();
    }
}

Stack trace:

com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.gmail.com, 465; timeout -1;
  nested exception is:
    java.net.ConnectException: Connection timed out: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1984)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:656)
    at javax.mail.Service.connect(Service.java:345)
    at javax.mail.Service.connect(Service.java:226)
    at com.karmacrafts.util.CustomEmail.main(CustomEmail.java:127)
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(Unknown Source)
    at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:301)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:229)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1950)
    ... 4 more

回答1:

This looks like network problem. Even though it could occur due to variety of reasons, like :-

"Couldn't connect to host, port" could be caused by wrong host name, wrong port, a blocking firewall (on the server, on gateways, even on your own machine), network failure, server downtime, etc.

Can you connect to the mail server using telnet ?

Also see this FAQ for some mistakes you committed http://www.oracle.com/technetwork/java/javamail/faq/index.html#commonmistakes

Read this answer on how to send emails using gmail https://stackoverflow.com/a/47452/3107043

回答2:

Session session = Session.getInstance(props, new javax.mail.Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
    return new PasswordAuthentication(username, password);
}
});   
props.put("mail.smtp.port", "587");  transport.send(message);