Print out custom field and footer in newsletter
$node is available within the simplenews templates. htmlmail-simplenews.tpl.php is a generic template that is not simplenews specific.

$body in this context is the mail body, which has been created by combining the simplenews body and footer. Again, within Simplenews, those are separated, but are then simply concatenated together before passed to the htmlmail template.

To get to the node object in there, look at the example templated provided by HTML Mail, which uses $params['context']['node'] and $params['simplenews_source']-&gt;getNode() in Drupal 7.