2013: USPS Scans & Retains All Mail

Mr. Pickering was targeted by a longtime surveillance system called mail covers, a forerunner of a vastly more expansive effort, the Mail Isolation Control and Tracking program, in which Postal Service computers photograph the exterior of every piece of paper mail that is processed in the United States — about 160 billion pieces last year. It is not known how long the government saves the images.

Together, the two programs show that postal mail is subject to the same kind of scrutiny that the National Security Agency has given to telephone calls and e-mail.

The mail covers program, used to monitor Mr. Pickering, is more than a century old but is still considered a powerful tool. At the request of law enforcement officials, postal workers record information from the outside of letters and parcels before they are delivered. (Opening the mail would require a warrant.) The information is sent to the law enforcement agency that asked for it. Tens of thousands of pieces of mail each year undergo this scrutiny.

The Mail Isolation Control and Tracking program was created after the anthrax attacks in late 2001 that killed five people, including two postal workers. Highly secret, it seeped into public view last month when the F.B.I. cited it in its investigation of ricin-laced letters sent to President Obama and Mayor Michael R. Bloomberg. It enables the Postal Service to retrace the path of mail at the request of law enforcement. No one disputes that it is sweeping.

“In the past, mail covers were used when you had a reason to suspect someone of a crime,” said Mark D. Rasch, who started a computer crimes unit in the fraud section of the criminal division of the Justice Department and worked on several fraud cases using mail covers. “Now it seems to be, ‘Let’s record everyone’s mail so in the future we might go back and see who you were communicating with.’ Essentially you’ve added mail covers on millions of Americans.”