import javax.mail.Authenticator;
import javax.mail.PasswordAuthentication;
public class Email_Autherticator extends Authenticator {
  String username = "你邮箱的用户名";
  String password = "你邮箱的密码";
  public Email_Autherticator() {
 super();
  }
  public Email_Autherticator(String user,String pwd){
 super();
 username = user;
 password = pwd;
  }
  public PasswordAuthentication getPasswordAuthentication(){
 return new PasswordAuthentication(username,password);
  }
}

import java.util.Date;
import java.util.Properties;
import javax.mail.Address;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.SendFailedException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
public class Mail {
  private String host = "smtp.126.com";
  private String mail_head_name = "this is head of this mail";
  private String mail_head_value = "this is head of this mail";
  private String mail_to = "254173774@qq.com";
  private String mail_from = "hackboyo@126.com";
  private String mail_subject = "this is the subject of this test mail";
  private String mail_body = "this is mail_body of this test mail";
  private String personalName = "我的邮件";
  public void sendMail() throws SendFailedException{
 try {
   Properties props = new Properties();//获取系统环境
   Authenticator auth = new Email_Autherticator();//进行邮件服务用户认证
   props.put("mail.smtp.host", host);
   props.put("mail.smtp.auth", "true");
   System.out.println(props);
   Session session = Session.getDefaultInstance(props,auth);
   //设置session,和邮件服务器进行通讯
   MimeMessage message = new MimeMessage(session);
   message.setContent("Hello","text/plain");//设置邮件格式
   message.setSubject(mail_subject);//设置邮件主题
   message.setText(mail_body);//设置邮件内容
   message.setHeader(mail_head_name, mail_head_value);//设置邮件标题
   message.setSentDate(new Date());//设置邮件发送时期
   Address address = new InternetAddress(mail_from,personalName);
   message.setFrom(address);//设置邮件发送者的地址
   Address toaddress = new InternetAddress(mail_to);//设置邮件接收者的地址
   message.addRecipient(Message.RecipientType.TO,toaddress);
   System.out.println(message);
   Transport.send(message);
   System.out.println("Send Mail Ok!");
 } catch (Exception e) {
   e.printStackTrace();
 }
 //return flag;
  }
}

public class Test {
  public static void main(String[] args) {
 Mail m = new Mail();
 try {
   m.sendMail();
 } catch (Exception e) {
 }
  }
}