Master Spring Boot Email Activation & Password Recovery: Full Code Guide

1. Introduction

In many projects, features such as user registration, email activation and password recovery are widely used to improve user experience and enhance system security.

Account Activation

After registration the system sends an activation link via email; clicking the link changes the account status from inactive to active. The benefits are:

Prevent malicious registrations.

Verify the validity of the user's email address.

Increase user trust.

Password Recovery

The feature allows users who forget their password to reset it after verification, improving user experience and enhancing system security.

Improve user experience.

Enhance security through captcha, email verification, and other mechanisms.

2. Practical Example

This example uses the QQ mail server to send emails.

2.1 QQ Mail Configuration

Configure the QQ mailbox as follows (screenshots omitted).

2.2 Project Configuration

Add the mail starter dependency:

<code>&lt;dependency&gt;
  &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
  &lt;artifactId&gt;spring-boot-starter-mail&lt;/artifactId&gt;
&lt;/dependency&gt;</code>

Configure mail properties (application.yml):

<code>spring:
  mail:
    host: smtp.qq.com
    username: [email protected]
    # the authorization code generated in QQ mail, not the QQ password
    password: xxxoooxxxooo
    protocol: smtp
    # port 465 does not work
    port: 587
    # additional timeout settings
    properties:
      '[mail.smtp.connectiontimeout]': 5000
      '[mail.smtp.timeout]': 3000
      '[mail.smtp.writetimeout]': 5000</code>

2.3 Sending Template Email

Define a bean for the email template:

<code>@Bean
SimpleMailMessage mailMessage(MailProperties mailProperties) {
  SimpleMailMessage mailMessage = new SimpleMailMessage();
  mailMessage.setSubject("Spring Full Stack Demo – Account Activation");
  mailMessage.setFrom(mailProperties.getUsername());
  return mailMessage;
}</code>

Service method to send the activation mail (asynchronous):

<code>@Resource
private JavaMailSender mailSender;
@Resource
private SimpleMailMessage templateMessage;

@Async
public void accountActivation(User user) {
  SimpleMailMessage msg = new SimpleMailMessage(this.templateMessage);
  msg.setTo(user.getMail());
  msg.setText("Thanks " + user.getName() + ", you have registered for the Spring Full Stack Demo. Please click the link to activate your account.");
  try {
    this.mailSender.send(msg);
  } catch (MailException ex) {
    System.err.printf("Mail send error: %s%n", ex.getMessage());
  }
}</code>

Test method:

<code>@Test
public void testAccountActivation() throws Exception {
  User user = new User();
  user.setMail("[email protected]");
  user.setName("Pack");
  user.setUsername("jaapack");
  this.mailService.accountActivation(user);
  System.in.read();
}</code>

2.4 Sending Attachments

<code>@Async
public void sendAttachments(User user) throws Exception {
  MimeMessage message = this.mailSender.createMimeMessage();
  MimeMessageHelper helper = new MimeMessageHelper(message, true);
  helper.setFrom(mailProperties.getUsername());
  helper.setTo(user.getMail());
  helper.setSubject("Gift – Spring Boot Project Collection");
  helper.setText("Thanks " + user.getName() + ", enjoy the Spring Boot project collection PDF.");
  FileSystemResource file = new FileSystemResource(new File("f:/SpringBoot项目实战案例锦集.pdf"));
  helper.addAttachment("SpringBoot项目实战案例锦集.pdf", file);
  this.mailSender.send(message);
}</code>

2.5 Sending Inline Resources

<code>@Async
public void sendInlineResource(User user) throws Exception {
  MimeMessage message = this.mailSender.createMimeMessage();
  MimeMessageHelper helper = new MimeMessageHelper(message, true);
  helper.setFrom(mailProperties.getUsername());
  helper.setTo(user.getMail());
  helper.setSubject("Inline Resource Demo");
  helper.setText("Thanks <b>" + user.getName() + "</b>, check this image:<br/><img src='cid:id_un_123'/>", true);
  FileSystemResource res = new FileSystemResource(new File("d:/images/1.png"));
  helper.addInline("id_un_123", res);
  this.mailSender.send(message);
}</code>

Important: add the text content before adding inline resources, and set the second parameter of setText to true to indicate HTML content.