The Harvard Police said that it could not trace the origin of the mail or its authenticity. However, it is reported to have raised an alert around the university's campus centered in Cambridge, Massachusetts, just outside Boston, over the weekend.
Meanwhile, Boston area residents have been placed on high alert since two home-made bombs were set off at the city's marathon in April 2013, killing three people and injuring 260.
The university police said that they had alerted the FBI and the local law enforcement. A similar situation had occurred last December when the campus was evacuated, following a fake bomb call. This later turned out to be a student trying to avoid final exams.