Proxmox VE is an Open Source solution for running virtual devices including, virtual machines, containers and more. It is perfect and almost a necessity for lab environments but is powerful and robust enough for the most demanding production environment
Emulac can be used as a definition of our ™Neural Micro Services and can be categorized as follows: Isn't conscious, is pretending to be. Isn't conscious, isn't pretending to be. Is conscious, is pretending not to be - Scary movie stuff! Is conscious...is conscious.
Proxmox Mail Gateway or PMG is a shell that provides a neat interface for Sendmail / Postfix. It adds a number of features but also adds quite a bit of complexity. It will be rare for you to find a PMG specific article describing how to fix a Sendmail configuration issue or how to setup a PMG system from scratch never-mind getting it to work properly and then monitoring the system.
SMTP Email is ubiquitous but the setup can be very complicated. This feature post will assist you in setting up the infrastructure.