Guide to Spring Email – 春天的电子邮件指南

最后修改: 2017年 1月 15日

1. Overview


In this tutorial, we’ll walk through the steps needed to send emails from both a plain vanilla Spring application as well as a Spring Boot application. For the former, we’ll use the JavaMail library, and the latter will use the spring-boot-starter-mail dependency.

在本教程中,我们将介绍从普通的vanilla Spring应用程序和Spring Boot应用程序中发送电子邮件所需的步骤。对于前者,我们将使用JavaMail库,而后者将使用spring-boot-starter-mail依赖项。

2. Maven Dependencies


First, we need to add the dependencies to our pom.xml.


2.1. Spring


Here is what we’ll add for use in the plain vanilla Spring framework:

下面是我们要添加的内容,以便在普通的vanilla Spring框架中使用。


The latest version can be found here.


2.2. Spring Boot


And for Spring Boot:

而对于Spring Boot。


The latest version is available in the Maven Central repository.

最新版本可在Maven Central资源库中找到。

3. Mail Server Properties


The interfaces and classes for Java mail support in the Spring framework are organized as follows:


  1. MailSender interface: the top-level interface that provides basic functionality for sending simple emails
  2. JavaMailSender interface: the subinterface of the above MailSender. It supports MIME messages and is mostly used in conjunction with the MimeMessageHelper class for the creation of a MimeMessage. It’s recommended to use the MimeMessagePreparator mechanism with this interface.
  3. JavaMailSenderImpl class provides an implementation of the JavaMailSender interface. It supports the MimeMessage and SimpleMailMessage.
  4. SimpleMailMessage class: used to create a simple mail message including the from, to, cc, subject and text fields
  5. MimeMessagePreparator interface provides a callback interface for the preparation of MIME messages.
  6. MimeMessageHelper class: helper class for the creation of MIME messages. It offers support for images, typical mail attachments and text content in an HTML layout.

In the following sections, we show how to use these interfaces and classes.


3.1. Spring Mail Server Properties


Mail properties that are needed to specify, for example, the SMTP server may be defined using the JavaMailSenderImpl.


For Gmail, this can be configured as shown below:


public JavaMailSender getJavaMailSender() {
    JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
    Properties props = mailSender.getJavaMailProperties();
    props.put("mail.transport.protocol", "smtp");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");
    props.put("mail.debug", "true");
    return mailSender;

3.2. Spring Boot Mail Server Properties

3.2.Spring Boot邮件服务器属性

Once the dependency is in place, the next step is to specify the mail server properties in the file using the spring.mail.* namespace.


We can specify the properties for the Gmail SMTP server this way:

我们可以这样指定Gmail SMTP服务器的属性。
spring.mail.username=<login user to smtp server>
spring.mail.password=<login password to smtp server>

Some SMTP servers require a TLS connection, so we use the property to enable a TLS-protected connection.


3.2.1. Gmail SMTP Properties

We can send an email via Gmail SMTP server. Have a look at the documentation to see the Gmail outgoing mail SMTP server properties.

我们可以通过Gmail SMTP服务器发送电子邮件。请看一下文档,看看Gmail的外发邮件SMTP服务器属性。

Our file is already configured to use Gmail SMTP (see the previous section).

我们的application.properties文件已经被配置为使用Gmail SMTP(见上节)。

Note that the password for our account should not be an ordinary password but an application password generated for our Google account. Follow this link to see the details and to generate your Google App Password.


3.2.2. SES SMTP Properties

To send emails using Amazon SES, we set our

为了使用Amazon SES发送电子邮件,我们设置我们的

Please be aware that Amazon requires us to verify our credentials before using them. Follow the link to verify your username and password.


4. Sending Email


Once dependency management and configuration are in place, we can use the aforementioned JavaMailSender to send an email.


Since both the plain vanilla Spring framework as well as the Boot version of it handle the composing and sending of emails in a similar way, we won’t have to distinguish between the two in the subsections below.


4.1. Sending Simple Emails


Let’s first compose and send a simple email message without any attachments:


public class EmailServiceImpl implements EmailService {

    private JavaMailSender emailSender;

    public void sendSimpleMessage(
      String to, String subject, String text) {
        SimpleMailMessage message = new SimpleMailMessage(); 

Note that even though it’s not mandatory to provide the from address, many SMTP servers would reject such messages. That’s why we use the email address in our EmailService implementation.

请注意,即使不是必须提供from地址,许多SMTP服务器也会拒绝这样的邮件。这就是为什么我们在EmailService实现中使用 电子邮件地址。

4.2. Sending Emails With Attachments


Sometimes Spring’s simple messaging is not enough for our use cases.


For example, we want to send an order confirmation email with an invoice attached. In this case, we should use a MIME multipart message from JavaMail library instead of SimpleMailMessage. Spring supports JavaMail messaging with the org.springframework.mail.javamail.MimeMessageHelper class.


First of all, we’ll add a method to the EmailServiceImpl to send emails with attachments:


public void sendMessageWithAttachment(
  String to, String subject, String text, String pathToAttachment) {
    // ...
    MimeMessage message = emailSender.createMimeMessage();
    MimeMessageHelper helper = new MimeMessageHelper(message, true);
    FileSystemResource file 
      = new FileSystemResource(new File(pathToAttachment));
    helper.addAttachment("Invoice", file);

    // ...

4.3. Simple Email Template


SimpleMailMessage class supports text formatting.


We can create a template for emails by defining a template bean in our configuration:


public SimpleMailMessage templateSimpleMessage() {
    SimpleMailMessage message = new SimpleMailMessage();
      "This is the test email template for your email:\n%s\n");
    return message;

Now we can use this bean as a template for email and only need to provide the necessary parameters to the template:


public SimpleMailMessage template;
String text = String.format(template.getText(), templateArgs);  
sendSimpleMessage(to, subject, text);

5. Handling Send Errors


JavaMail provides SendFailedException to handle situations when a message cannot be sent. But it is possible that we won’t get this exception while sending an email to the incorrect address. The reason is the following:


The protocol specs for SMTP in RFC 821 specifies the 550 return code that the SMTP server should return when attempting to send an email to the incorrect address. But most of the public SMTP servers don’t do this. Instead, they send a “delivery failed” email or give no feedback at all.

RFC 821中的SMTP协议规范规定了SMTP服务器在试图向不正确的地址发送邮件时应返回的550返回代码。但大多数公共SMTP服务器并不这样做。相反,他们会发送一封 “发送失败 “的电子邮件,或者根本不给出任何反馈。

For example, Gmail SMTP server sends a “delivery failed” message. And we get no exceptions in our program.

例如,Gmail的SMTP服务器会发送一个 “发送失败 “的消息。而我们的程序中没有得到任何例外。

So, we have a few options to handle this case:


  1. Catch the SendFailedException, which can never be thrown.
  2. Check our sender mailbox for the “delivery failed” message for some period of time. This is not straightforward, and the time period is not determined.
  3. If our mail server gives no feedback at all, we can do nothing.

6. Conclusion


In this quick article, we showed how to set up and send emails from a Spring Boot application.

在这篇快速文章中,我们展示了如何在Spring Boot应用程序中设置和发送电子邮件。

The implementation of all these examples and code snippets can be found over on GitHub.