We've had an open/automated invite system for our Slack community since we started it in summer 2015. Two years later, we have a strong community of 3,300+ members. Our community and discussions are mostly focused on engineering and we have a shared passion for building decentralized apps. In recent months, we've seen a lot of phishing attacks and attempts to promote various crypto tokens that are not relevant to our community. To better protect our community against phishing attacks and to maintain the quality of our discussions, we're switching from an automated invite system to a process where new users will submit 1-2 lines about why they want to join our Slack and we'll manually approve the request. Our intention is to filter out spammers and we don't expect to deny many requests.