how to disable services on the docker image?

Hi everybody!

I am trying to find the cleanest way to disable services (like pop3-login, pop3, etc.) in the docker image, if possible extending the existing configuration with conf.d files. Is this possible? I have tried using the protocol keyword on those services, after setting the protocols to that ones I want, and the services still get instantiated (thus consuming resources as well).

Thank you! Felix