Before we start let's see how to prepare our machine for the installation. What follows is mostly a collection of hints that I extracted from the comments, so feel free to contribute.
On Debian 11, you may have to install at least these packages:
apt install build-essential autoconf automake libmariadb-dev default-libmysqlclient-dev libidn2-dev
You can decide to install a wider set of packages, if your installation doesn't provide the webserver and the database:
apt install sudo git autoconf automake build-essential libssl-dev libmariadb-dev default-libmysqlclient-dev mariadb-server \ libev-dev unzip help2man net-tools apache2 python-dev-is-python3 fcgiwrap apache2-utils libnet-ssleay-perl php php-fpm php-zip
This is the list of packages to install on Ubuntu 22.04:
apt install build-essential autoconf automake libmariadb-dev libmariadb-dev-compat wget man help2man unzip psmisc libexpat-dev libidn2-dev
Installing rc.local as a systemd service
In the following guide, our services (not only qmail) will be launched at boot time via rc.local, which is dismissed on a systemd OS. So let's create a new rc.local executable and define it as a systemd service.
Create rc.local and make it executable:
cat > /etc/rc.local << __EOF__ #!/bin/bash -e __EOF__ chmod +x /etc/rc.local
Create the systemd service:
cat > /etc/systemd/system/rc-local.service << __EOF__ [Unit] Description=/etc/rc.local ConditionPathExists=/etc/rc.local [Service] Type=forking ExecStart=/etc/rc.local TimeoutSec=0 StandardOutput=tty RemainAfterExit=yes [Install] WantedBy=multi-user.target __EOF__
Enable and start:
systemctl enable rc-local systemctl start rc-local
