Online email services are especially vulnerable, with companies like Google and Yahoo essentially rolling over for the feds. As the Associated Press reported:
"So not only did the FBI - again, all without any real evidence of a crime - trace the locations and identity of Broadwell and Petreaus, and read through Broadwell's emails (and possibly Petraeus'), but they also got their hands on and read through 20,000-30,000 pages of emails between Gen. Allen and Kelley.
This is a surveillance state run amok. It also highlights how any remnants of internet anonymity have been all but obliterated by the union between the state and technology companies.
The downfall of CIA Director David Petraeus demonstrates how easy it is for federal law enforcement agents to examine emails and computer records if they believe a crime was committed. With subpoenas and warrants, the FBI and other investigating agencies routinely gain access to electronic inboxes and information about email accounts offered by Google, Yahoo and other Internet providers."