org.springframework.boot
  spring-boot-starter-mail

# JavaMailSender 邮件发送的配置
spring.mail.host=smtp.163.com
spring.mail.username=用户163邮箱
spring.mail.password=邮箱密码
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.smtp.starttls.required=true

@RunWith(SpringRunner.class)
@SpringBootTest
@ActiveProfiles("163")
public class EmailTest {

  @Autowired
  private JavaMailSender mailSender; //自动注入的Bean

  @Value("${spring.mail.username}")
  private String Sender; //读取配置文件中的参数

  @Test
  public void sendSimpleMail() throws Exception {
    SimpleMailMessage message = new SimpleMailMessage();
    message.setFrom(Sender);
    message.setTo(Sender); //自己给自己发送邮件
    message.setSubject("主题：简单邮件");
    message.setText("测试邮件内容");
    mailSender.send(message);
  }
}

  @Test
  public void sendHtmlMail() {
    MimeMessage message = null;
    try {
      message = mailSender.createMimeMessage();
      MimeMessageHelper helper = new MimeMessageHelper(message, true);
      helper.setFrom(Sender);
      helper.setTo(Sender);
      helper.setSubject("标题：发送Html内容");

      StringBuffer sb = new StringBuffer();
      sb.append("
大标题-h1
")
          .append("
红色字
")
          .append("
右对齐
");
      helper.setText(sb.toString(), true);
    } catch (Exception e) {
      e.printStackTrace();
    }
    mailSender.send(message);
  }

  @Test
  public void sendAttachmentsMail() {
    MimeMessage message = null;
    try {
      message = mailSender.createMimeMessage();
      MimeMessageHelper helper = new MimeMessageHelper(message, true);
      helper.setFrom(Sender);
      helper.setTo(Sender);
      helper.setSubject("主题：带附件的邮件");
      helper.setText("带附件的邮件内容");
      //注意项目路径问题，自动补用项目路径
      FileSystemResource file = new FileSystemResource(new File("src/main/resources/static/image/picture.jpg"));
      //加入邮件
      helper.addAttachment("图片.jpg", file);
    } catch (Exception e){
      e.printStackTrace();
    }
    mailSender.send(message);
  }

  @Test
  public void sendInlineMail() {
    MimeMessage message = null;
    try {
      message = mailSender.createMimeMessage();
      MimeMessageHelper helper = new MimeMessageHelper(message, true);
      helper.setFrom(Sender);
      helper.setTo(Sender);
      helper.setSubject("主题：带静态资源的邮件");
      //第二个参数指定发送的是HTML格式,同时cid:是固定的写法
      helper.setText("带静态资源的邮件内容 图片:", true);

      FileSystemResource file = new FileSystemResource(new File("src/main/resources/static/image/picture.jpg"));
      helper.addInline("picture",file);
    } catch (Exception e){
      e.printStackTrace();
    }
    mailSender.send(message);
  }

   
     org.springframework.boot
     spring-boot-starter-freemarker
   

  @Autowired
  private FreeMarkerConfigurer freeMarkerConfigurer; //自动注入

  @Test
  public void sendTemplateMail(){
    MimeMessage message = null;
    try {
      message = mailSender.createMimeMessage();
      MimeMessageHelper helper = new MimeMessageHelper(message, true);
      helper.setFrom(Sender);
      helper.setTo(Sender);
      helper.setSubject("主题：模板邮件");

      Map model = new HashedMap();
      model.put("username", "zggdczfr");

      //修改 application.properties 文件中的读取路径
//      FreeMarkerConfigurer cOnfigurer= new FreeMarkerConfigurer();
//      configurer.setTemplateLoaderPath("classpath:templates");
      //读取 html 模板
      Template template = freeMarkerConfigurer.getConfiguration().getTemplate("mail.html");
      String html = FreeMarkerTemplateUtils.processTemplateIntoString(template, model);
      helper.setText(html, true);
    } catch (Exception e) {
      e.printStackTrace();
    }
    mailSender.send(message);
  }