' . $this->t('About') . ''; $output .= '

' . $this->t('The Mailer module provides an experimental API to build and deliver email messages based on Symfony mailer component. For more information, see the online documentation for the Mailer module.', [ ':mailer' => 'https://www.drupal.org/docs/core-modules-and-themes/experimental-extensions/experimental-modules/mailer', ]) . '

'; return $output; default: return NULL; } } }