No Private medical data

I keep receiving one of their clients medical related emails, they state you can not reply to these emails as no one will read it, they give another email address which I have infomed them on. Yet they still share this client's medical data with me even though I have told them that it's the wrong address. Should get hold of the client and tell them so they could sue this medical aid for sharing their personal medical information with strangers and when told they are continuing doing so.