[efesak]

You can try https://hub.docker.com/r/analogic/poste.io/ - Its complete easy to use solution installed with docker... see https://poste.io/ (author here)

[TheDong]

Ugh, closed source.

mailserver is a part of my stack I need to be able to tweak and look behind the curtain at; one-size-fits-all is really hard with email.