public function getMailboxes()
    {
        $uri = 'mailboxes';
        $response = $this->client->getEndpoint()->get($uri);

        $mailboxes = [];
        foreach (\GuzzleHttp\json_decode($response->getBody()) as $mailbox) {
            $mailboxes[] = new Mailbox($mailbox);
        }

        return $mailboxes;
    }