How to add headers to outgoing email?
Thanks to the above, I’ve realized my central mistake — I didn’t quite realize that the arguments being passed in were a multi-dimensional array. For now, I’ve re-implemented the function thus: function ws_add_site_header($email) { $email[‘headers’][] = ‘X-WU-Site: ‘ . parse_url(get_site_url(), PHP_URL_HOST) ; return $email; } My reading of the wp_mail() source (see: https://core.trac.wordpress.org/browser/tags/4.4.2/src/wp-includes/pluggable.php#L235) leads me … Read more