@lightweight @thegibson Luckily it was off-season for them, so there were no customer enquiries to track; and the only thing they'd been using email for was organising new uniforms from a supplier; so the supplier would have had all the copies of correspondence. So they were as mellow as possible under the circumstances!

In a technical interview a few years later I was asked "what's the worst thing you've done to a customer?" so I told the story. "What would you do differently?" was the next question, so I said I'd change the prompt on the old and new server using something like the MAC address to check (as that's the only unique identifier). The unix beard nodded, and said "yes, that's what I did when I had a job like that; but I got the prompts the wrong way around ..."

So I got that job :-)

I keep that question for interviews with people who have had sysadmin responsibility, it's a good one.