The covered entity (CE), the VA St. Louis Health Care System, reported that an employee mistakenly mailed letters that contained the protected health information (PHI) of 595 individuals, to the wrong recipients. The PHI involved included names, addresses, and treatment information. The CE notified HHS, affected individuals, and the media. In its mitigation efforts, the CE re-trained the responsible employee and implemented new mail procedures to better protect its PHI.