protected static function mergeConfiguredEmails($config, $env)
    {
        // Normalise config list
        $normalised = [];
        $source = (array)static::config()->get($config);
        foreach ($source as $address => $name) {
            if ($address && !is_numeric($address)) {
                $normalised[$address] = $name;
            } elseif ($name) {
                $normalised[$name] = null;
            }
        }
        $extra = Environment::getEnv($env);
        if ($extra) {
            $normalised[$extra] = null;
        }
        return $normalised;
    }