无法连接到 SMTP 主机：smtp.gmail.com，端口：Windows Server 2016 上的 587

Question

I am trying to send an email from a gmail account from windows server 2016 from a Java application and I get the error : "Could not connect to SMTP host: smtp.gmail.com, port: 587."

When trying on my local machine, which runs windows 10, the code works perfectly. I have used mail enable and port 587 is enabled and also used as an alternate port to listen to for SMTP. Also, I configured an inbound rule for this port on windows server. I still have the same error. Does anyone know what I can do ?

I will also add the code.

package email;

import java.sql.Timestamp;
import java.util.Properties;

import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;


public class GoogleMail {

    public void sendEmail(String emailContent) {

        final String username = "findyourbets2020@gmail.com";
        final String password = "*********";

        Properties props = new Properties();
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");

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

        try {

            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("findyourbets2020@gmail.com"));
            message.setRecipients(Message.RecipientType.TO,
                    InternetAddress.parse("testemail@gmail.com"));
            Timestamp timestamp = new Timestamp(System.currentTimeMillis());
            message.setSubject("Application Failed at" + timestamp);
            message.setText(emailContent);

            Transport.send(message);

            System.out.println("Done");

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}

Answer 1

Is that gmail account configured to allow 'unsecure apps'? You may need to setup an app token to allow such direct connections to gmail.