At last, postal workers are vindicated.  The happy, stout-legged men and women of America's quietest bureaucracy have long been maligned for the bloody outbursts of a few co-workers, who, when they went crazy, did so at work. But a few weeks ago, a federal commission formed to study the topic found that postal workers are in less physical danger than college professors.  You might have missed it. But you can bet the mail carriers didn't. Over the last 10 years, the US. Postal Service instituted multiple anti-violence tactics. They even sued the makers of the now-banned video game "Postal," in which the player is a murderous postal worker who takes over a station, holds hostages and blows away SWAT teams.  Not that the carriers took this reputation very seriously. In fact, the postal workers of my acquaintance are a remarkably mellow and sane bunch. Perhaps it's the daily cardiovascular workout. Perhaps it's the uniform, vaguely reminiscent of Catholic school. Perhaps it's the Zen task of moving large numbers of envelopes from one location to the next. The color blue is known to be soothing. So these folks can cope with all sorts of abuse. "No, I don't mind the term 'go postal,' said one Langhorne letter carrier. "I'm used to it by now."  "Sometimes customers joke about it," said a Levittown clerk. He lifted his hands up in a gesture of mock terror, saying, "Sometimes they do this and say, `please don't shoot me!' But I'm not bothered by it."  "Ten years ago it used to be a pretty hostile environment, though," said one 33-year veteran named O'Malley. "There was a lot of friction between labor and management. A lot of it boiled over in (those incidents.)"  The postal service aside, there is an incredible amount of workplace violence in America. Nearly 2 million incidents a year. Almost 1,000 murders, according to OSHA, many of which result from liquor stores being robbed at 3 a.m. Is work turning America into a nation of murderous beasts?  Profiteers believe that it is. There are hundreds and hundreds of consultants and companies selling workplace safety to companies in the form of huge binders, books, seminars, training sessions. But as with everything else, there's only so much they can do. The people who are really responsible for the bulk of workplace violence are all of us - the public.  The more people, money and midnights there are in a job, the greater the risk. The top five riskiest jobs, according to OSHA, are police officer, private security guard, taxicab driver, prison guard, and bartender. So all of you out daydreaming about going to bartending school, consider.  And think twice before you threaten violence when that kid screws up your latte. He might just take it out on a poor postal worker.