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An example of an email which has been changed by an external source is displayed on a computer screen in this arranged photograph in Tunis, Tunisia, on Sunday, Oct. 2, 2011. Tunisia's surveillance capabilities put it at the forefront of a technological arms race in which repressive regimes are gaining increasing power to monitor - and manipulate - citizens' electronic activities. Photographer: Shawn Baldwin/Bloomberg via Getty Images

An example of an email which has been changed by an external source is displayed on a computer screen in this arranged photograph in Tunis, Tunisia, on Sunday, Oct. 2, 2011. Tunisia's surveillance capabilities put it at the forefront of a technological arms race in which repressive regimes are gaining increasing power to monitor - and manipulate - citizens' electronic activities. Photographer: Shawn Baldwin/Bloomberg via Getty Images