Java mail has connection errors

问题:

I'm trying to send an email using my java application, but it always gives me a connection error back. So my code looks like this:

import java.util.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;

public class SendMail {

public static void main(String [] args) {

    String to = "[e-mail]";
    String from = "[e-mail]";
    String host = "localhost";

    Properties properties = System.getProperties();
    properties.setProperty("mail.user", "fromsomeone");
    properties.setProperty("mail.password", "passwordForSomeone");
    properties.setProperty("mail.smtp.host", host);

    Session session = Session.getDefaultInstance(properties);


    try {

        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
        message.setSubject("subject typed");
        message.setText("This is actual message which is just some lines");
        Transport.send(message);

    }catch (MessagingException mex) {
        mex.printStackTrace();
    }
}
}

of course I provide valid information (using my gmail account). And this is the error I get back:

com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;
  nested exception is:
java.net.ConnectException: Connection refused (Connection refused)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2118)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:712)
at javax.mail.Service.connect(Service.java:366)
at javax.mail.Service.connect(Service.java:246)
at javax.mail.Service.connect(Service.java:195)
at javax.mail.Transport.send0(Transport.java:254)
at javax.mail.Transport.send(Transport.java:124)
at email.SendMail.main(SendMail.java:49)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
Caused by: java.net.ConnectException: Connection refused (Connection refused)
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:331)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:238)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2084)
... 12 more

Can someone help me, what is wrong with my code? Thank you!

回答1:

This will be help you to send mail via gmail account;

public class MailMan {
Session session = null;

public MailMan() {
    if (session == null) {
        init();
    }
}

public void init() {

    Properties props = new Properties();
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.port", "465");

    session = Session.getDefaultInstance(props, new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication("EMAIL", "PASSWORD");
        }
    });
    if (session != null) {
        System.out.println("[OK]");
    } else {
        System.out.println("[NOK]");
    }
}

public void sendMail() {
    if (session == null) {
        System.exit(0);
    }
    try {
        String messageText = "";
        Message message = new MimeMessage(session);
        try {
            message.setFrom(new InternetAddress("no-reply", "No Reply"));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        message.setReplyTo(InternetAddress.parse("no-reply"));


        message.addRecipients(Message.RecipientType.TO, InternetAddress.parse("to_email")); 
        message.setSubject("TEST");
        message.setText(messageText);

        Transport.send(message);

        System.out.println("[OK]");

    } catch (MessagingException e) {
        e.printStackTrace();
        System.out.println("Not Sent...");
    }
 }
}

And the main class;

public class SendMail {

public static void main(String[] args) {
    MailMan ma = new MailMan();
    ma.sendMail();

  }
}

After all you should turn on your "Access for less secure apps".

回答2:

Can you try changing:

properties.setProperty("mail.smtp.host", host);

to:

properties.setProperty("mail.smtp.host", "smtp.gmail.com");