Just made a big mistake that affects system operations. Tell me your past mistakes to help me feel less bad..

Not a system analyst, but a security analyst. Just got off a call with my boss because I blocked a legitimate noreply email address that is exploited a lot, but also used for legit business purposes. We had 2400 rejected messages, with no way to verify what was spam and what was legit. Potential company wide notice has to be sent out informing users that they might have missed documents and to see if they can get a hold of people to get them resent. Boss said it's "one of the most dangerous things that can happen from a business ops standpoint." How is everyone else's Friday going?