This week a hard disk from one of my servers broke. It has been replaced with just 3 minutes of downtime (kudos to OVH), and right now the RAID array is being rebuilt.
Since this is the first time this happens to me, and the server is running a production mailman service, I decided to take my time and set-up a backup MX server. This is how I did it.
Remember that I am using a Gentoo distribution, this may be slightly different in other distro.