Phishing emails cost companies millions. In the absence of technology to perfectly block phishing emails, the responsibility falls on employees to identify and appropriately respond to phishing attempts and on employers to train them to do so. We report results from an experiment with around 11,000 employees of a large U.S. corporation, testing the efficacy of just-in-time feedback delivered at a teachable moment – immediately after succumbing to a phishing email – to reduce susceptibility to phishing emails. Employees in the study were sent an initial pseudo-phishing email, and those who either ignored or fell victim to the phishing email were randomized to receive or not receive feedback about their response. Just-in-time feedback for employees who fell victim to or ignored the initial pseudo-phishing email reduced susceptibility to a second pseudo-phishing email sent by the research team. Additionally, for employees who ignored the initial email, feedback also increased reporting rates.