Add an option to send HTML format opt-in / subscribe mails

Having same issue

1) Need to ensure the email is formatted as HTML
Swiftmailer settings allow you to change for every message the site sends: /admin/config/swiftmailer/messages change the message format to HTML and remove respect provided format.

Can do it smarted in hook_mail something like this

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

2) Need to ensure the HTML doesn't get stripped or escaped.
At the moment you might get lucky because I think the required escaping is missing - see #3031910: Corruption of subscribe mails that look like HTML.

It would be best to add an option to the module to make it work easily.

Reroll

Using SimpleMail on D9, I cannot switch to any text format other than Plain Text on
/admin/config/swiftmailer/messages

I can set 'content type' to HTML, but the 'HTML Format' option list doesn't even show any other options than 'Plain Text'.

Any hints?

@nofue Sorry I'm not sure this patch is entirely finished/working yet.

Same issue with 3.x-dev with Drupal 9

Problem:

<p>We have received a request for the following subscription changes for <a href="mailto:xxxxxxxxxxxx">xxxxxxx@xxxxxx.com</a> at <a href="http://localhost/xxxxxxxxxxxx/:">http://localhost/xxxxxxxxx/:</a></p>
<p> - &lt;p&gt;Subscribe to Default newsletter&lt;/p&gt;</p>
<p>To confirm please use the link below.</p>
<p><a href="http://localhost/xxxxxxxxxxxxxxxxx">http://localhost/xxxxxxxxxxxxxxxxxxxxxx…</a></p>

Solution:
Reroll patch as per @AdamPS

Working fine with Drupal 9 version

"drupal/simplenews": "3.x-dev@dev",
......
"patches": {
            "drupal/simplenews" : {
                "HTML format Subscription email fix" : "https://www.drupal.org/files/issues/2021-07-05/simplenews-3003811-html_subscription_email_format_fix-3_x_dev-11.patch"
            }
        },

Go to : /admin/config/services/simplenews/settings/subscription
and change the Text format "Full HTML"

update version hook_update_830005()

Thanks for the patches. Set to "Needs work" as latest patch failed to apply - please can you reroll or fix?

You guess you meant to this "Needs work" ;)

In the meantime, others needing to send the email as HTML can use the hook_mail_alter like this:

/**
 * Implements hook_mail_alter().
 */
function MYMODULE_mail_alter(&$message) {
  switch ($message['key']) {
    case 'page_mail':
    case 'page_copy':
    case 'cancel_confirm':
    case 'password_reset':
    case 'register_admin_created':
    case 'register_no_approval_required':
    case 'register_pending_approval':
    case 'register_pending_approval_admin':
    case 'status_activated':
    case 'status_blocked':
    case 'register_confirmation_with_pass':
    case 'status_canceled':
    case 'subscribe':
      $message['headers']['Content-Type'] = 'text/html; charset=UTF-8; format=flowed; delsp=yes';
      foreach ($message['body'] as $key => $body) {
        $message['body'][$key] = new FormattableMarkup($body, []);
      }
      break;

  }
}

Re-rolled patch from #13. Please have a look.

Thanks I'll take a look as soon as I get a chance

Patch is good thanks. Next step this needs tests before commit.

I suggest there should be a new test SimplenewsSubscribeTest::testHtml() something like this.

1. Enable HTMLTestingMailSystem (see SimplenewsSourceTest::testSendHtml())
2. Log in as admin user and set confirm_combined_body to contain HTML
3. Log out and subscribe - the HTML should be escaped
4. Log in as admin user and set text_format to basic_html
5. Log out and subscribe - the HTML should be unaltered

Probably won't fix this - instead plan to move simplenews to use Symfony Mailer module.

#17 little edited for work now.

Rerolled patch for simplenews 3.0.0-beta4

Problem still exists and the provided patch solves it. Please reconsider a fix!

Please see #21 - the proposed solution is to use Symfony Mailer, which is now a beta release with 4.5k sites using. Any reason why you can't use it??

Swiftmailer is no longer supported anyway. It doesn't seem to make sense to add features that are only useful in that case. I would like to close this as "won't fix".

I've made a fork and a merge request (!75) thanks to the patch in comment #24. Tested on Drupal 9.5.11, Simplenews version 4.0.0 and also with the Drupal Symfony Mailer module. This patch solved the problem.

Please see #21 / #25.