At work, we used to run a small in house tuck shop type of chocolate and sweetie box. The price of everything was inside the lid and an honesty jar was at the side. Week after week, the honesty jar was "short" of money, which could only mean that someone was being dishonest. My boss asked me to send an email to all staff, telling them that if it happened again, he would remove the tuck shop and he was disappointed that we had a dishonest person/people amongst us. I duly wrote a stiff email and sent it to "ALL". I'd failed to notice that "ALL" meant everyone I'd ever sent an email to and it went to clients, solicitors, accountants and suppliers. I was besieged for weeks with random people asking if the tuck shop was still going or had been shut down. Never made that mistake again.