It's been a while since the last update (stuck into 0.8.6), an update was needed!
The virtual machine now provides the latest version (0.9.2) and includes a functional amavisd-new setup.
you'll find it here. Enjoy :)
The virtual machine image has been updated due to an issue with gunicorn startup. This service was not started correctly, the result was that modoboa could not be accessed.
For those who do not want to download the whole image again, you can just apply the following modification to your existing image.
Sorry for the noise...