In early 2011, the CEO of a French IT company issued an usual memorandum. He banned email. Employees were discouraged from sending or receiving internal messages, with the goal of eradicating email within 18 months. Critics scoffed. Workers rebelled. But Thierry Breton, the CEO of Atos, has stuck to his guns, reducing message volume by an estimated 20 percent. His company, by the way, has 74,000 employees in 48 countries.