emails/api/setup/settings/02_folders.php

<?php
use Psr\Container\ContainerInterface;

return [
    'base_folder' => function() {
        return dirname(__FILE__, 3);
    },
    'resources_folder' => function(ContainerInterface $container) {
        return implode(DIRECTORY_SEPARATOR, [
            $container->get('base_folder'),
            'resources'
        ]);
    },
    'routes_folder' => function(ContainerInterface $container) {
        return implode(DIRECTORY_SEPARATOR, [
            $container->get('resources_folder'),
            'routes'
        ]);
    },
    'attachments_folder' => $_ENV['ATTACHMENTS_FOLDER'],
    'logs_folder' => '/logs',
];