Two Vietnamese citizens and a Canadian have been charged with running a massive cyberfraud ring that stole 1 billion email addresses, then sent spam offering knockoff software products, the U.S. Department of Justice said on Friday. The Justice Department described the hacking spree as "one of the largest" data breaches uncovered in U.S. history. It declined to name the email companies that were victimized, though it appeared that the breaches included a massive 2011 attack on email marketing firm Epsilon. Security blogger Brian Krebs reported that Epsilon, a unit of Alliance Data Systems Corp, was among the victims. That high-profile 2011 attack was followed by a wave of customer notifications from Epsilon clients, including　Citigroup　Inc.　and　JPMorgan Chase & Co.