NemoWeb

In September 2016, almost 21GB of data from the French website used for "standardised and decentralized means of exchange for publishing newsgroup articles" NemoWeb was leaked from what appears to have been an unprotected Mongo DB. The data consisted of a large volume of emails sent to the service and included almost 3.5M unique addresses, albeit many of them auto-generated. Multiple attempts were made to contact the operators of NemoWeb but no response was received.