My Domino war story isn’t as interesting as some of these, but:
At a company I worked for, an intern mangled a bit of lotusscript into an unintentional virus that forwarded the entire contents of his inbox to every email address in the company, causing a reply storm that took a week to recover from.
Early in IBM's internal rollout, I worked for IBM - I demoed to one of IBM's security guys how to embed a button in an email to all users within IBM that would delete their own mailbox when clicked. (Did not actually send it, of course)
His reaction was, "Oh, shit." I don't know who he talked to, or if it was just a coincidence, but Execution Control Lists came out really quick on the next version.
At a company I worked for, an intern mangled a bit of lotusscript into an unintentional virus that forwarded the entire contents of his inbox to every email address in the company, causing a reply storm that took a week to recover from.
From then on we called it Locust — a plague.