使用 javax.mail 发送大型电子邮件，某些电子邮件发送失败

Question

我使用 javax.mail 从我的域拥有的 SMTP 服务器向用户发送大量电子邮件（大约 1000 封）。并且所有收件人都在同一个域电子邮件中。

发送邮件时，如果只有成功，那么我将令牌保存在 userToken 表中。否则我不会将令牌保存在表中。处理完成后，userToken表插入950行，表示所有email都成功。

我编写了以下代码来发送批量电子邮件，但用户没有收到近 300 封电子邮件。执行时我没有收到任何错误，

@RequestMapping(value = "bulkMail")
public  @ResponseBody  String bulkMail(Model model, HttpServletRequest request,@RequestParam(value="myArray") Long[] myArray, HttpServletResponse response) throws IOException {
    Session session = null;
    EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("roca");
    EntityManager entityManager = entityManagerFactory.createEntityManager();
    entityManager.getTransaction().begin();
    HttpSession httpSession = request.getSession(false);
    session = getRocaSession();
    Test test = (Test) httpSession.getAttribute("test");

    for (int i = 0; i < myArray.length; i++) {
        User user = entityManager.createQuery( "SELECT u FROM User u where u.userId=" + myArray[i], User.class).getSingleResult();

        UserToken userToken;
        try {
            userToken = entityManager.createQuery("SELECT ut FROM UserToken ut where ut.testId="+test.getId()+" and ut.userId="+myArray[i], UserToken.class).getSingleResult();
        } catch (Exception e) {
            userToken = new UserToken();
        }

        String mailStatus = sendMail(userToken,test,request, user.getUserId(),  user.getUserName(), context, user.getEmailId(),session);
        if (!mailStatus.equals("failure")) {
            userToken.setToken(mailStatus);
            userToken.setCreatedDate(new Date());
            userToken.setUpdatedDate(new Date());
            userToken.setTestId(test.getId());
            userToken.setUserId(user.getUserId());
            userToken.setUsed(0);
            testDao.saveOrUpdate(userToken);
        }
    }
    entityManager.getTransaction().commit();
    entityManager.close();
    return "Emails have been send to Users";
}

发送电子邮件

public String sendMail(UserTestToken userTestToken, Test test,HttpServletRequest request, Long accountId,String accountName,
        String context,String accountEmail,Session session) {
    String token = getToken();
    try {
        String email = mailService.sendAlert(test, accountEmail,"User Triger", "noreply@mydomain.com", "Val", accountId, token, context, accountName, session);
        if (!email.equals("failure")) {
            return token;
        }else {
            return "failure";
        }
    } catch (Exception e) {
        return "failure";
    }       
}

获取电子邮件会话

public Session getSession() {
    Properties props = new Properties();
    props.put("mail.smtp.auth", "false");
    props.put("mail.smtp.host", "gatesmtp.moc.domain.com");
    props.put("mail.smtp.port", "25");
    Session session = Session.getInstance(props);
    session.setDebug(false);
    return session;
}

邮件服务实现

public String sendTestMailAlert(Test test, String accountEmail, String receiverName, String senderEmail, String url, Long accountId, String token, String context, String       accountName, Session session)
{
    String subject = "Subject";
    String content = "Content";
    return sendMail(accountEmail, content, subject, receiverName, senderEmail, session);
}


private String sendMail(String receiverMailIds, String content, String subject, String employeeName, String employeeEmail, Session session) {
    try {
        Message message = new MimeMessage(session);
        try {
            message.setFrom(new InternetAddress(employeeEmail, employeeName));
        } catch (UnsupportedEncodingException e) {
            this.logger.error("Mail service address catch UnsupportedEncodingException");
        }
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(receiverMailIds));
        message.setSubject(subject);
        message.setContent(content, "text/html");
        Transport.send(message);
        return "success";
    } catch (Exception e) {
        this.logger.error("Mail Exception - " + receiverMailIds);
    }
    return "failure";
}

Answer 1

问题不在您的代码中：如果邮件在您的邮件服务器中正确排队，则问题出在最终收件人的 SMTP 服务器上。

当您的 SMTP 服务器（必须正确发送邮件的队列）联系收件人 SMTP 服务器时，可能（肯定...）收件人 SMTP 出于某些原因拒绝电子邮件（垃圾邮件？未知用户？邮件太多？邮箱已满？）。因此，您的 SMTP 服务器无法传递电子邮件，并尝试将其发送回发件人（您定义为“noreply@domain.com”）。如果此邮箱不存在，您的 SMTP 服务器会删除邮件并（通常）仅在其内部日志上记录该操作。这就是为什么你无法注意到发生了什么。

您可以使用真实的发件人地址而不是 noreply 来进行测试。

玩得开心:)