“Trello had an open API endpoint that allows any unauthenticated user to map an email address to a trello account”
A hacker called emo fed 500 million email addresses into an unauthenticated Trello API and got back 15,115,516 matching profiles with full names. The full dump now sells for eight forum credits, about $2.32. Atlassian closed the endpoint in January, after the scraping was done. Rate limits stop nobody who rents a few hundred proxies.