Only getting email bin attachment, collision with swiftmailer hook_mail params

There's a patch here, can you review and report back? https://www.drupal.org/files/issues/2022-08-08/3219682-n1.patch

#3219682: Add support for HTML emails is related (the patch is from there)

Over there someone else reported the same issue as you

https://git.drupalcode.org/project/workbench_email/-/merge_requests/12/d... is where we map html to text/html - can you debug that and see if your site isn't running that?

Can you check the format key of your templates is set to HTML?

Hmm, that sounds like you have some other module interfering then
Do you have any other modules that implement hook_mail_alter or similar?

It looks like Swiftmailer is setting the wrong Content-type header, due to a parameter which is passed since Workbench Email 2.3.0.

In WorkbenchEmailProcessor, the format is passed to the $params array:

        $this->mailManager->mail('workbench_email', 'template::' . $template->id(), $data->getTo(), LanguageInterface::LANGCODE_DEFAULT, [
          'body' => $body,
          'template' => $template,
          'subject' => $subject,
          'format' => $format,
          'entity' => $entity,
        ], $replyTo);

It contains either text_plain or html, but Swiftmailer seems to expect a mime type instead. In \Drupal\swiftmailer\Plugin\Mail\SwiftMailer::getContentType(), we have this:

    // The message parameter takes priority over config. Support the alternate
    // parameter 'format' for back-compatibility.
    $content_type = $message['params']['content_type'] ?? $message['params']['format'] ?? $this->config['message']['content_type'];
    // 1) check the message parameters.
    if ($content_type) {
      return $content_type;
    }

Here, the $message['params']['format'] contains the string html, which is taken for the Content-type header.

Not sure if this is a bug of SwiftMailer or the new functionality in Workbench Email, but we can work around this by additionally passing a real content type to $this->mailManager->mail(). Attaching a first patch.

Reducing the change footprint in the patch so it can be applied together with #3017273: Recipient Type Email Field does not work for translated content, always uses original language value..

Ah, so if the issue is that 'format' collides with a key used by Swiftmailer, how about we name it something else in $params?

E.g. template_format or similar?

I'm not sure what the purpose of adding the format to the $params array in #3219682: Add support for HTML emails was, but in order not to break even more, I thought it was a better idea to add the content_type key additionally, which I knew would be caught by Swiftmailer in favor of format.

This should do the trick, and is much smaller patch

I'm not changing a config element. I'm just changing what we pass to hook_mail - another reason why this option is a lighter touch

Nice!
I wasn't aware that the format parameter was only by coincidence named equally to what SwiftMailer expects, and that its only purpose was to be handled in hook_mail.

RTBC+1.

Nice, I'll wrap this up and release it tomorrow (evening here now)

Tagging 2.3.1 - thanks