Mumbai, Nov. 13 -- A bomb threat email was received by the office of Mumbai Mayor Ritu Tawde threatening to target her office, actor Amitabh Bachchan, singer-actor Diljit Dosanjh and several city-based schools, police said, adding that the responsibility for the email has been claimed by an outfit that calls itself Khalistan National Army (KNA). The police said they conducted the required checks on receipt of the email and nothing suspicious was found. The email was received by the Mayor's office at 11.30 am on Thursday. The email threatened to target the Mayor's office at 3 pm, the schools at 1 pm, Bachchan's Jalsa bungalow in Juhu from October 31 to November 27. The police suspect KNA is the same group that has been sending hoax emails ov...