HTML tags not supported when sending emails in Drupal 8

Question

This is my code to sending email

   function hook_mail($key, &$message, $params) {
     $options = array(
    'langcode' => $message['langcode'],
  );

  switch ($key) {
    case 'create_article':
      $message['from'] = \Drupal::config('system.site')->get('mail');
      // $message['headers']['Cc'] = $params['cc'];

      $message['subject'] = 'SUBJECT';
      $message['body'][] = Markup::create($params['message']);
      break;
  }
}

Mails are getting without any issue.But some of the HTML tags are not supporting Eg: HTML bold,italics.... I have also configured SMTP authentication.

Answer 1

You can't send HTML email with Drupal 8 "out of the box."

To send HTML email, you can use the Swift Mailer module, which has the following features:

• Sending e-mails directly through a SMTP server of your choice, a locally installed MTA agent such as sendmail or the mail functionality provided by PHP.
• Sending HTML (MIME) e-mails.
• Adding file attachments to e-mails.
• Adding inline images to e-mails.

The Commerce 2 documentation includes a tutorial on how to install and configure the Swift Mailer module.

Answer 2

In D7 you need to install Mime Mail and in your code add:

$message['headers']['Content-Type'] = 'text/html; charset=UTF-8; format=flowed';

Hopefully it's still the same on D8, give it a try.