I worked for a European energy company, and an email to all employees was sent in one of the directors names. Some fool "replied all" with their branespeak, and in a company with over 40,000 employees copied in, a small additional number of fuckwits were persuaded that this was a good way to raise their profile. This snowballing of bilge rapidly threatened to take down the entire IT infrastructure, until the CEO waded in and sent an email to all employees, promising that the next person using "reply all" to company wide email would find a compulsory meeting with him in their Outlook calendar, including paid travel to the German head office.
Surprising how many people suddenly realised that it was possible to NOT "reply all" - although only for a few days. I've concluded that "reply all" is the digital equivalent of liking the sound of your own voice.