Yahoo Inc last year secretly built a custom software program to search all of its customers' incoming emails for specific information provided by U.S. intelligence officials, according to people familiar with the matter.
Mayer and Yahoo General Counsel Ron Bell did not involve the company's security team in the process, instead asking Yahoo's email engineers to write a program to siphon off messages containing the character string the spies sought and store them for remote retrieval, according to the sources.
More than one mistake in that series of events.