function hook_mail
Prepares a message based on parameters;
This hook is called from MailManagerInterface->mail(). Note that hook_mail(), unlike hook_mail_alter(), is only called on the $module argument to MailManagerInterface->mail(), not all modules.
Parameters
$key: An identifier of the mail.
$message: An array to be filled in. Elements in this array include:
- id: An ID to identify the mail sent. Look at module source code or MailManagerInterface->mail() for possible id values.
 - to: The address or addresses the message will be sent to. The formatting of this string must comply with RFC 2822.
 - subject: Subject of the email to be sent. This must not contain any newline characters, or the mail may not be sent properly. MailManagerInterface->mail() sets this to an empty string when the hook is invoked.
 - body: An array of lines containing the message to be sent. Drupal will format the correct line endings for you. MailManagerInterface->mail() sets this to an empty array when the hook is invoked. The array may contain either strings or objects implementing \Drupal\Component\Render\MarkupInterface.
 - from: The address the message will be marked as being from, which is set by MailManagerInterface->mail() to either a custom address or the site-wide default email address when the hook is invoked.
 - headers: Associative array containing mail headers, such as From, Sender, MIME-Version, Content-Type, etc. MailManagerInterface->mail() pre-fills several headers in this array.
 
$params: An array of parameters supplied by the caller of MailManagerInterface->mail().
See also
\Drupal\Core\Mail\MailManagerInterface::mail()
Related topics
11 functions implement hook_mail()
Note: the procedural functions in this list are found by pattern matching, so the list may include some functions that are not actually implementations of this hook.
- ContactHooks::mail in core/
modules/ contact/ src/ Hook/ ContactHooks.php  - Implements hook_mail().
 - contact_mail in core/
modules/ contact/ contact.module  - Implements hook_mail().
 - MailHtmlTestHooks::mail in core/
modules/ system/ tests/ modules/ mail_html_test/ src/ Hook/ MailHtmlTestHooks.php  - Implements hook_mail().
 - mail_html_test_mail in core/
modules/ system/ tests/ modules/ mail_html_test/ mail_html_test.module  - Implements hook_mail().
 - SystemHooks::mail in core/
modules/ system/ src/ Hook/ SystemHooks.php  - Implements hook_mail().
 
File
- 
              core/
core.api.php, line 2074  
Code
function hook_mail($key, &$message, $params) {
  $account = $params['account'];
  $context = $params['context'];
  $variables = [
    '%site_name' => \Drupal::config('system.site')->get('name'),
    '%username' => $account->getDisplayName(),
  ];
  if ($context['hook'] == 'taxonomy') {
    $entity = $params['entity'];
    $vocabulary = Vocabulary::load($entity->id());
    $variables += [
      '%term_name' => $entity->name,
      '%term_description' => $entity->description,
      '%term_id' => $entity->id(),
      '%vocabulary_name' => $vocabulary->label(),
      '%vocabulary_description' => $vocabulary->getDescription(),
      '%vocabulary_id' => $vocabulary->id(),
    ];
  }
  // Node-based variable translation is only available if we have a node.
  if (isset($params['node'])) {
    /** @var \Drupal\node\NodeInterface $node */
    $node = $params['node'];
    $variables += [
      '%uid' => $node->getOwnerId(),
      '%url' => $node->toUrl('canonical', [
        'absolute' => TRUE,
      ])
        ->toString(),
      '%node_type' => node_get_type_label($node),
      '%title' => $node->getTitle(),
      '%teaser' => $node->teaser,
      '%body' => $node->body,
    ];
  }
  $subject = strtr($context['subject'], $variables);
  $body = strtr($context['message'], $variables);
  $message['subject'] .= str_replace([
    "\r",
    "\n",
  ], '', $subject);
  $message['body'][] = MailFormatHelper::htmlToText($body);
}
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