This happened in 2013 when I was with a company in asia, which I think had more than 100,000 employees globally.
So, there was this email distribution list that IT hadn't updated in ages. Someone from a different country sent an email to it around 8 PM my time. He inquired about something. By the time I started my shift the next day, my inbox was overflowing with more than 3,000 emails!!!! All in less than 12 hours!
Turns out, every single one of the 100,000+ employees was on that list. Everyone was replying, “Please take me off this distribution list. I'm not the right contact person” to “Please stop replying to ALL!”
I still have those emails. Whenever I need a laugh, I just revisit that email thread.