Deploy OpenDMARC to your postfix server
As a MTA lover, I always try to encourage people (especially "IT-people") to host their own mailserver. Mostly so they actually can learn something and also that I do not like how the big providers like Google, Microsoft, Amazon etc keep eating up the market. Diversity is a key to a healthy market - but that is another topic. This guide will mostly apply to Debian-based distros like Debian (9 or newer), Ubuntu (16.04 or newer) or any other serverdistro. I do assume that you already have a working mailserver that do both deliver and receive emails that are DKIM signed (or atleast perform validation with OpenDKIM), otherwhise you can read my short guide here (coming soon). First, install OpenDMARC from the repository. apt update apt install opendmarc -y Verify that the user and group "opendmarc" has been created by checking /etc/passwd and /etc/group. Otherwhise, create them. When you have installed it, verify the installation by running this: opend...