https://hub.docker.com/r/boky/postfix/
https://github.com/jeremybusk/docker-postfix
https://github.com/mail-in-a-box/mailinabox
https://github.com/eldada/postfix-relay-kubernetes
https://github.com/catatnight/docker-postfix
https://github.com/juanluisbaptiste/docker-postfix best?
https://github.com/jessfraz/dockerfiles/tree/master/postfix