Question: In what year became publicly known that the 67th Unitades States Secretary of States had used her family's private email server for official communications?
Sentence (from "Hillary Clinton email controversy"): In March 2015, it became publicly known that Hillary Clinton, during her tenure as United States Secretary of State, had used her family's private email server for official communications, rather than official State Department email accounts maintained on federal secure servers.
Relevant evidence: Yes