Here's a pro-tip: If you write an article about how to set up a mail server and do so with a test-bed server specifically intended for testing and mucking about, remember not to wipe your actual, real, 'production' mail server by accident when you think it's time to wipe the test-bed server.
Admittedly, one IP address can look much like another at 7AM, but it's still no excuse!
On the up-side, at least I can attest that my article is pretty accurate and functional: I had a rebuilt server available in less than 20 minutes by following my own advice there!
Unfortunately, I lost all my mail archives, which is a bit of a bummer. Would pay to remember to set up a backup routine before relying on a server, instead of adding it to the list of 'things to get around to'.
Of course, you only stuff up like that once in a lifetime, yes?!