api, #cybersecurity, #webdev, #python The 250 OK Lie I Measured Last Tuesday Last Tuesday I ran a small experiment: I took 50 email addresses that had already passed two layers of validation, regex syntax and a live SMTP handshake, and 48 of them returned 250 OK . I then sent a real, plain-text message to each one. Twelve bounced. Not rejected at the gate. Not caught by spam filters. Bounced. If you've ever trusted RCPT TO as the final word on deliverability, that number s...