One would click on a bogus email, and it would automatically spread the virus to everyone in your address book. The only real damage it did was to overwhelm the system with thousands of bogus emails, thus slowing the servers to a crawl.
It took maybe six months to get that under control. It was mostly a matter of education. If you didn't recognize the sender, don't open it, delete it, and notify the webmaster.
ILOVEYOU, a.k.a., VBS/Loveletter, a.k.a., Love Bug.