首先要在maven添加javamail支持

<dependency>

 <groupId>javax.activation</groupId>

 <artifactId>activation</artifactId>

 <version>1.1</version>

</dependency>

<dependency>

 <groupId>javax.mail</groupId>

 <artifactId>mail</artifactId>

 <version>1.4</version>

</dependency>
不加的话会报javax.mail.MessagingException异常   

代码如下  ：

 1 package com.learn.util;

 /**

  * Created by Wangqingyu on 2017/6/3.

  */

 import javax.mail.*;

 import javax.mail.internet.AddressException;

 import javax.mail.internet.InternetAddress;

 import javax.mail.internet.MimeMessage;

 import java.util.Date;

 import java.util.Properties;

 public class SendEmailUtil  {

     //获取用于发送邮件的Session

    public static Session  getSession() throws MessagingException {

        //创建连接对象 连接到邮件服务器

        Properties props = new Properties();

        //设置发送邮件的基本参数

        //发送邮件服务器

        props.put("mail.smtp.host", "smtp.163.com");

        props.put("mail.store.protocol" , "smtp");//设置协议

        //发送端口

        props.put("mail.smtp.port", "25");

        props.put("mail.smtp.auth", "true");

        Authenticator authenticator = new Authenticator() {

            @Override

            protected PasswordAuthentication getPasswordAuthentication() {

                return new PasswordAuthentication("邮件发自的邮箱@163.com","邮件发自的邮箱授权码");

            }

        };

        Session session = Session.getDefaultInstance(props, authenticator);

        return session;

    }

     //发送邮件，String email为邮件的目标邮箱

     public static void send(String email, String sb) throws MessagingException{

         Session session = getSession();

         try {

             Message msg = new MimeMessage(session);

             //设置message属性

             msg.setFrom(new InternetAddress("邮件发自的邮箱@163.com"));

            //InternetAddress[] addrs = {new InternetAddress(email)};

             msg.setRecipient(Message.RecipientType.TO, new InternetAddress(email));

             msg.setSubject("贵宾xxx先生");//邮箱标题

             msg.setSentDate(new Date());//邮箱时间

             msg.setContent(sb, "text/html;charset=utf-8");//邮箱内容和格式

                //必须为text/html;格式，纯文本格式会被当做垃圾邮件

             //开始发送

             Transport.send(msg);

         } catch (AddressException e) {

             e.printStackTrace();

         } catch (MessagingException e) {

             e.printStackTrace();

         }

     }

 }

注意的点：上文中提到的邮箱授权码而不是密码，是因为邮件的发自邮箱需要设置POP3/SMTP/IMAP服务，否则会报503异常
具体如何设置可自行百度。