In hindsight some teacher must have spoken up for me to come up with the solution when they were trying to come up with an appropriate response.
I had to go apologise to IT (who could barely keep a straight face) at college for sending a message from 'God' saying "I saw what you did last night and it disgusted me".
I thought it was going to just the lab but since I was poking around in something I really didn't understand I manage to send it out site wide.
Fortunately they saw the funny side.
Around the same time, someone at my school made a much, much worse semi-accidental prank. Semi-accidental because he didn't think it would work. See, the campus list serve was setup to only allow certain senders to send messages. Makes sense, only a few top administrators should be able to do that. This person theorized that a simple <smtp: from> hack, using an authorized person's email, might circumvent the restriction. He was right! Unfortunately, rather than "test 1 2 3" or something, he sent a message, from the president, that all classes had been cancelled. Had he stopped there, maybe it would have been chalked up to a prank. But he went further: The president would be using this free time to, um, entertain amorous visitors at their leisure. So, yeah, expelled. His excuse, when interviewed by the student newspaper, was "I didn't think it would work."
I've been able to do it at every university I've studied or worked at.
I'm actually not sure anymore what the details of their return email was, as it was over 25 years ago. But it was basically, "We will report you to law enforcement if you contact us again."