What is the origin of the idiom "go postal" and when to use it?

The idiom "go postal" originated in the United States in the 1990s. It gained prominence due to a series of highly publicized incidents involving acts of violence committed by postal workers. These incidents occurred in various locations across the United States, and the media coverage surrounding them popularized the term "going postal." The phrase specifically refers to instances where individuals employed by the U.S. This phrase is used in informal contexts to describe a situation or behavior involving an extreme and violent outburst or display of anger. It is typically employed when referring to instances of workplace violence or when someone exhibits uncontrollable rage or aggression.