FYI

A dear friend recently received an email from an obviously disturbed individual who "wanted to kill her." Such threats cannot be ignored. As this article points out, "Senders can be mentally unstable or under the influence of drugs or alcohol, or other unknown factors may be at play. It is better to take a threat seriously and have no outcome than to ignore it and find yourself in trouble later."

Sending threatening emails or messages through the Internet using instant messages or other means is a federal crime in the U.S. Statute 18 U.S.C. § 875(c) states: "Whoever transmits in interstate or foreign commerce any communication containing any threat to kidnap any person or any threat to injure the person of another, shall be fined under this title or imprisoned not more than five years, or both." Intent is beside the point -- the act of sending the threatening email is a punishable offense. Learn what to do if you receive emails that threaten you,

Read more : http://www.ehow.com/how_5061920_handle-email-threats.html

There are some people, arrogant or ignorant, who think they can hide in cyber space. Any one who has been threatened in any form should know they have recourse. 

You can also file a complain with the FBI  here's the link. http://www.ic3.gov/default.aspx