@Service
public class EmailService {
    
    @Autowired
    private JavaMailSender mailSender;
    
    public void sendEmailWithAttachment(
            String to, 
            String subject, 
            String body, 
            String attachmentPath) throws MessagingException {
        
        MimeMessage message = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(message, true); // true = multipart
        
        helper.setTo(to);
        helper.setSubject(subject);
        helper.setText(body);
        helper.setFrom("your-email@gmail.com");
        
        // Add attachment
        FileSystemResource file = new FileSystemResource(new File(attachmentPath));
        helper.addAttachment(file.getFilename(), file);
        
        mailSender.send(message);
    }
}

public void sendHtmlEmailWithInlineImage() throws MessagingException {
    MimeMessage message = mailSender.createMimeMessage();
    MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
    
    helper.setTo("recipient@example.com");
    helper.setSubject("HTML Email with Image");
    
    String htmlContent = "
Welcome!
Here is our logo:
";
    helper.setText(htmlContent, true); // true = isHtml
    
    // Add inline image
    FileSystemResource image = new FileSystemResource("path/to/logo.png");
    helper.addInline("logoImage", image);
    
    mailSender.send(message);
}

helper.setTo("user1@example.com", "user2@example.com");  // TO
helper.setCc("cc@example.com");  // Carbon Copy
helper.setBcc("bcc@example.com"); // Blind Carbon Copy

@Autowired
private SpringTemplateEngine templateEngine;

public void sendTemplateEmail(String to, String templateName, Context context) throws MessagingException {
    String htmlContent = templateEngine.process(templateName, context);
    // ... set htmlContent to helper.setText(htmlContent, true)
}

• Use MimeMessage and MimeMessageHelper for complex emails.
• MimeMessageHelper constructor with true enables multipart (attachments).
• addAttachment() adds file attachments.
• addInline() adds inline images referenced with cid: in HTML.
• setText(html, true) sends HTML emails.
• Support TO, CC, BCC for multiple recipients.