spring-mail

What this skill does

# Spring Mail

## Quick Start

```yaml
# application.yml
spring:
  mail:
    host: smtp.gmail.com
    port: 587
    username: ${MAIL_USERNAME}
    password: ${MAIL_PASSWORD}
    properties:
      mail:
        smtp:
          auth: true
          starttls:
            enable: true
```

```java
@Service
@RequiredArgsConstructor
public class EmailService {

    private final JavaMailSender mailSender;

    public void sendSimpleEmail(String to, String subject, String text) {
        SimpleMailMessage message = new SimpleMailMessage();
        message.setTo(to);
        message.setSubject(subject);
        message.setText(text);
        message.setFrom("[email protected]");

        mailSender.send(message);
    }
}
```

---

## Configuration

```java
@Configuration
public class MailConfig {

    @Bean
    public JavaMailSender javaMailSender(MailProperties props) {
        JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
        mailSender.setHost(props.getHost());
        mailSender.setPort(props.getPort());
        mailSender.setUsername(props.getUsername());
        mailSender.setPassword(props.getPassword());

        Properties javaMailProperties = new Properties();
        javaMailProperties.put("mail.smtp.auth", true);
        javaMailProperties.put("mail.smtp.starttls.enable", true);
        javaMailProperties.put("mail.smtp.connectiontimeout", 5000);
        javaMailProperties.put("mail.smtp.timeout", 5000);
        javaMailProperties.put("mail.smtp.writetimeout", 5000);

        mailSender.setJavaMailProperties(javaMailProperties);
        return mailSender;
    }
}
```

---

## MimeMessage (HTML & Attachments)

```java
@Service
@RequiredArgsConstructor
@Slf4j
public class EmailService {

    private final JavaMailSender mailSender;

    // HTML Email
    public void sendHtmlEmail(String to, String subject, String htmlContent)
            throws MessagingException {
        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");

        helper.setTo(to);
        helper.setSubject(subject);
        helper.setText(htmlContent, true);  // true = HTML
        helper.setFrom("[email protected]");

        mailSender.send(message);
    }

    // Email con attachment
    public void sendEmailWithAttachment(String to, String subject, String text,
                                        String attachmentPath) throws MessagingException {
        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true);

        helper.setTo(to);
        helper.setSubject(subject);
        helper.setText(text);
        helper.setFrom("[email protected]");

        FileSystemResource file = new FileSystemResource(new File(attachmentPath));
        helper.addAttachment(file.getFilename(), file);

        mailSender.send(message);
    }

    // Email con inline image
    public void sendEmailWithInlineImage(String to, String subject,
                                         String htmlContent, String imagePath)
            throws MessagingException {
        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true);

        helper.setTo(to);
        helper.setSubject(subject);
        // Reference: <img src="cid:logo">
        helper.setText(htmlContent, true);
        helper.setFrom("[email protected]");

        FileSystemResource image = new FileSystemResource(new File(imagePath));
        helper.addInline("logo", image);

        mailSender.send(message);
    }

    // Multiple recipients
    public void sendToMultiple(String[] to, String[] cc, String[] bcc,
                               String subject, String text) throws MessagingException {
        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message);

        helper.setTo(to);
        if (cc != null) helper.setCc(cc);
        if (bcc != null) helper.setBcc(bcc);
        helper.setSubject(subject);
        helper.setText(text);
        helper.setFrom("[email protected]");

        mailSender.send(message);
    }
}
```

---

## Thymeleaf Templates

```java
@Service
@RequiredArgsConstructor
public class TemplateEmailService {

    private final JavaMailSender mailSender;
    private final TemplateEngine templateEngine;

    public void sendWelcomeEmail(String to, String userName) throws MessagingException {
        Context context = new Context();
        context.setVariable("userName", userName);
        context.setVariable("activationLink", "https://example.com/activate/123");

        String htmlContent = templateEngine.process("email/welcome", context);

        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");

        helper.setTo(to);
        helper.setSubject("Welcome to Our Platform!");
        helper.setText(htmlContent, true);
        helper.setFrom("[email protected]");

        mailSender.send(message);
    }

    public void sendOrderConfirmation(String to, Order order) throws MessagingException {
        Context context = new Context();
        context.setVariable("order", order);
        context.setVariable("items", order.getItems());
        context.setVariable("total", order.getTotal());

        String htmlContent = templateEngine.process("email/order-confirmation", context);

        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");

        helper.setTo(to);
        helper.setSubject("Order Confirmation #" + order.getId());
        helper.setText(htmlContent, true);
        helper.setFrom("[email protected]");

        mailSender.send(message);
    }
}
```

```html
<!-- templates/email/welcome.html -->
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
</head>
<body style="font-family: Arial, sans-serif;">
    <div style="max-width: 600px; margin: 0 auto; padding: 20px;">
        <h1 style="color: #333;">Welcome, <span th:text="${userName}">User</span>!</h1>
        <p>Thank you for joining our platform.</p>
        <p>Please click the button below to activate your account:</p>
        <a th:href="${activationLink}"
           style="display: inline-block; padding: 10px 20px; background-color: #007bff;
                  color: white; text-decoration: none; border-radius: 5px;">
            Activate Account
        </a>
    </div>
</body>
</html>
```

---

## Async Email Sending

```java
@Service
@RequiredArgsConstructor
@Slf4j
public class AsyncEmailService {

    private final JavaMailSender mailSender;
    private final TemplateEngine templateEngine;

    @Async("emailExecutor")
    public CompletableFuture<Void> sendEmailAsync(EmailRequest request) {
        try {
            MimeMessage message = mailSender.createMimeMessage();
            MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");

            helper.setTo(request.getTo());
            helper.setSubject(request.getSubject());
            helper.setText(request.getContent(), request.isHtml());
            helper.setFrom(request.getFrom());

            mailSender.send(message);
            log.info("Email sent successfully to: {}", request.getTo());

            return CompletableFuture.completedFuture(null);
        } catch (Exception e) {
            log.error("Failed to send email to: {}", request.getTo(), e);
            return CompletableFuture.failedFuture(e);
        }
    }

    @Async("emailExecutor")
    @Retryable(retryFor = MailException.class, maxAttempts = 3,
               backoff = @Backoff(delay = 1000, multiplier = 2))
    public void sendWithRetry(String to, String subject, String content) {
        SimpleMailMessage message = new SimpleMailMessage();
        message.setTo(to);