必须首先发出STARTTLS命令.使用Java和Google Apps发送电子邮件

import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendEmailWithSTARTTLS {

    public static void main(String[] args) {
        // 设置邮件服务器的属性
        Properties props = new Properties();
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "587");
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");

        // 获取邮件服务器的登录会话
        Session session = Session.getInstance(props, new javax.mail.Authenticator() {
            protected javax.mail.PasswordAuthentication getPasswordAuthentication() {
                return new javax.mail.PasswordAuthentication("your-email@gmail.com", "your-password");
            }
        });

        try {
            // 创建一个消息对象
            Message message = new MimeMessage(session);

            // 设置发件人和收件人
            message.setFrom(new InternetAddress("your-email@gmail.com"));
            message.setRecipients(Message.RecipientType.TO, InternetAddress.parse("recipient-email@example.com"));

            // 设置邮件的主题和内容
            message.setSubject("Test email with STARTTLS");
            message.setText("This is a test email sent using STARTTLS.");

            // 发送邮件
            Transport.send(message);

            System.out.println("Email sent successfully.");

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