["Journal of Consumer Affairs, Volume 60, Issue 2, Summer 2026. ", "\nABSTRACT\nAlmost one‐fifth of Americans are victims of mass marketing scams each year, including scams perpetrated through the mail. Interventions to prevent revictimization could alleviate costs to vulnerable groups, but evidence of the efficacy of specific intervention approaches is lacking. This study involved partnering with the United States Postal Inspection Service to conduct a randomized controlled trial experiment of a mailed counter‐marketing (CM) campaign designed to prevent repeat mail fraud victimization (N = 2253). CM messages were tailored to address vulnerabilities that drive victims to respond to scams and empower them to resist and report mail fraud. Effectiveness was determined by observing whether victims responded to subsequent mail scams over 4 months. Compared to no intervention, a CM intervention reduced revictimization rates by five percentage points (p = 0.029). Findings can be used by mail service organizations to launch larger scale CM campaigns to reduce losses from mail scams.\n"]