emails/ui/resources/routes/01_emails.php

<?php
use ProVM\Common\Controller\Emails;

$app->group('/emails', function($app) {
    $app->group('/mailbox/{mailbox_id}', function($app) {
        $app->get('[/]', [Emails::class, 'messages']);
    });
    $app->group('/message/{message_id}', function($app) {
        $app->get('[/]', [Emails::class, 'show']);
    });
    $app->get('/mailboxes', Emails::class);
    $app->get('[/]', Emails::class);
});