Alter an email message created with the drupal_mail() function.

hook_mail_alter() allows modification of email messages created and sent with drupal_mail(). Usage examples include adding and/or changing message text, message fields, and message headers.

Email messages sent using functions other than drupal_mail() will not invoke hook_mail_alter(). For example, a contributed module directly calling the drupal_mail_system()->mail() or PHP mail() function will not invoke this hook. All core modules use drupal_mail() for messaging, it is best practice but not mandatory in contributed modules.

Parameters

$message: An array containing the message data. Keys in this array include:

• 'id': The drupal_mail() id of the message. Look at module source code or drupal_mail() for possible id values.
• 'to': The address or addresses the message will be sent to. The formatting of this string will be validated with the PHP e-mail validation filter.
• 'from': The address the message will be marked as being from, which is either a custom address or the site-wide default email address.
• 'subject': Subject of the email to be sent. This must not contain any newline characters, or the email may not be sent properly.
• 'body': An array of strings containing the message text. The message body is created by concatenating the individual array strings into a single text string using "\n\n" as a separator.
• 'headers': Associative array containing mail headers, such as From, Sender, MIME-Version, Content-Type, etc.
• 'params': An array of optional parameters supplied by the caller of drupal_mail() that is used to build the message before hook_mail_alter() is invoked.
• 'language': The language object used to build the message before hook_mail_alter() is invoked.
• 'send': Set to FALSE to abort sending this email message.

See also

drupal_mail()

Related topics

File

drupal-7.x/modules/system/system.api.php, line 1974

Hooks provided by Drupal core and the System module.

Code

function hook_mail_alter(&$message) {
  if ($message['id'] == 'modulename_messagekey') {
    if (!example_notifications_optin($message['to'], $message['id'])) {
      // If the recipient has opted to not receive such messages, cancel
      // sending.
      $message['send'] = FALSE;
      return;
    }
    $message['body'][] = "--\nMail sent out from " . variable_get('site_name', t('Drupal'));
  }
}