In times of complexity and easy cloud computing - is it still value-able to maintain an on-prem mail cluster with open-source tools? We will showcase our approach to sizing and rolling out a complete and flexible mail infrastructures, highlight why we chose Ansible for IaC, our approach to template the configuration and automatic documentation generation. We continue to update and develop our roles to incorporate our best practices, develop new features and counter latest security threats. Our Ansible Playbooks and Roles to roll-out this full fledged E-Mail infrastructure are open-source and publicly available. The setups are maintained either by us, the customer with our support or also completely independent.