Did she call the police and report it?
The threats were sent to the school she was going to speak at. They called the police. From the Washington Post article:
According to university spokesman Tim Vitale, the university formulated a security plan when they knew Sarkeesian was coming, prior to her arrival. “We were going to not allow bags in at all,” Vitale said. Once the threat was sent, “We added officers, both uniform and undercover, and we were going to empty the room and sweep the room [for bombs].”
Vitale said Milne was overwhelmed Tuesday coordinating with the Logan, Utah, police force, as well as the FBI’s cyberterrorism task force and behavioral analysis unit, to track down the source of the threat and assess the probability the perpetrator would act on it.