It's meant to be configured with the described env variables and ready
for serving the webmail without first running through the installer.
So far the configuration options are limited but it's a start. Before
we now apply for an official image, I'd like your feedback and
suggestions what other configuration options would be worth to be
supported, especially when considering to use the docker image for
production environments, too.
So please give it a try and check the Dockerfile and entrypoint