When using WP CLI to update WordPress and plugins, the Newsletter plugin is generating a ton of warnings in includes/default.php.
Please consider changing line 14 from
$sitename = strtolower($_SERVER[‘SERVER_NAME’]);
to this:
$sitename = strtolower(wp_parse_url(home_url(),PHP_URL_HOST));
This gets the same information through the official WordPress interface and does not generate a bunch of warnings when used in an environment where $_SERVER isn’t available.