HTML mail message
MIME (Multipurpose Internet Mail Extensions) messages are a type of email format that allows for the inclusion of various content types, such as text, images, audio, and video, beyond just plain text.
Spring provides helper class MimeMessageHelper
We create MimeMessageHelperMimeMessageJavaMailSender
We can set email parameters, like from, to, subject and more importantly text as html (second parameter to setText is true) and pass it to JavaMailSender instance to send mime email messages.
We can add attachments and inline resources with appropriate methods.
| Ordering for inline resources is important and needs to come AFTER we set html text. Inline Content id needs to match html cid: attribute (in our example logo). |
@Service
@Value
public class SimpleMailService {
JavaMailSender javaMailSender;
public void hardcodedHtmlExample() throws MessagingException, FileNotFoundException {
MimeMessage message = javaMailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
helper.setFrom("noreply@example.com");
helper.setTo("user@gmail.com");
helper.setSubject("html mail with resources");
helper.addAttachment("junit-cheat-sheet.pdf", ResourceUtils.getFile("classpath:templates/mail/attachments/junit-cheat-sheet.pdf"));
helper.setText("<html><body><img src='cid:logo'></body></html>", true);
// Ordering is important for inlining
// we first need to add html text, then resources
helper.addInline("logo", ResourceUtils.getFile("classpath:templates/mail/attachments/email-logo.png"));
javaMailSender.send(message);
}
}If we check raw email we’ve send, we’ll confirm that Mime message are multipart messages with parts for every resource we’ve included.
From: noreply@example.com To: user@gmail.com Message-ID: <1800306724.2.1736589968522@host.docker.internal> Subject: html mail with resources MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_0_1871378379.1736589967410" ------=_Part_0_1871378379.1736589967410 Content-Type: multipart/related; boundary="----=_Part_1_2068167739.1736589967414" ------=_Part_1_2068167739.1736589967414 Content-Type: text/html;charset=UTF-8 Content-Transfer-Encoding: 7bit <html><body><img src='cid:logo'></body></html> ------=_Part_1_2068167739.1736589967414 Content-Type: image/png Content-Transfer-Encoding: base64 Content-Disposition: inline Content-ID: <logo> iVBORw0KGgoAAAANSUhEUgAAAgMAAADLCAYAAADz/5CnAAAKrGlDQ1BJQ0MgUHJvZmlsZQAASImV lwdQk9kWx+/3pTcCJFQpoTfpLYCU0AMoSAdRCUmAUEIMBKXYWVzBtSAizQK6SlFwLYCsFVGsKFhA .......
General method for sending html mails
General method for sending html mails with resources could take html and list of attachments and inline resources as parameter and look something like this:
@Service
@Value
public class SimpleMailService {
private static final String NO_REPLY_ADDRESS = "noreply@example.com";
JavaMailSender javaMailSender;
public record MailResource(String name, File file) {
}
public void sendHtml(String to,
String subject,
String htmlBody,
List<MailResource> inlines,
List<MailResource> attachments) throws MessagingException {
MimeMessage message = javaMailSender.createMimeMessage();
MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
helper.setFrom(NO_REPLY_ADDRESS);
helper.setTo(to);
helper.setSubject(subject);
if (Objects.nonNull(attachments)) {
for (MailResource attachment: attachments) {
helper.addAttachment(attachment.name, attachment.file);
}
}
helper.setText(htmlBody, true);
if (Objects.nonNull(inlines)) {
for (MailResource inline : inlines) {
helper.addInline(inline.name, inline.file);
}
}
javaMailSender.send(message);
}
}