By now, it’s not news that the National Security Agency was gathering information about U.S. citizens without warrants, judicial review, or even the knowledge of those whose information found its way into government databases. The NSA didn’t need to listen into calls to spy on you any more than the Postal Service needs to open you letters to track your activity.

The difference? The Postal Service has been doing it for much, much longer and rarely faced scrutiny.

The surveillance system, known as Mail Covers, allows law enforcement to request information about individual mail contained on the outside of envelopes or packages by simply filling out a request form — no warrant necessary.

When this program has faced legal challenges, the practice has generally been upheld on the argument that there is no expectation of privacy for information included on the outside of letters or packages.

Put simply, if the government wants to know the basics of your snail mail correspondence, online purchases, or just about anything else you might send or receive through the postal service, they can. The courts won’t do much to stop it.

In a twist, the United States Postal Service has recently tried to brand its modern practice of photographing every package and parcel that comes through its facilities as helpful. Just sign up for something called, unthreateningly, “ Informed Delivery” to figure out how to government is able to keep tabs on your mail.

When you do, you can “preview your mail” or at least “letter-sized mailpieces that are processed through USPS’ automated equipment.” What the means is that USPS will send you “greyscale images of the exterior, address side” of the mail once it’s been processed.

That’s actually a lot of information that offers significant details of your personal life.

To be clear, there are lots of legitimate uses for law enforcement investigations tracking mail. As evidenced by the ongoing investigation into suspicious packages with rudimentary pipe bombs sent to prominent political leaders, there’s plenty of opportunity for crime through the mail. The system was also key to the investigation into ricin-laced letters sent to President Barack Obama and New York Mayor Michael Bloomberg.

But the wide net of mail surveillance catches far much than the occasional would-be killer.

With the digital tracking system in place, initially designed to sort mail, the government can easily monitor everyone’s mail — not just those with an open request from law enforcement. And in 2007, President George W. Bush gave law enforcement the authority to open mail without a warrant in emergencies or foreign intelligence cases.

It’s great that bombs sent through the mail can be tracked, but it's critical to understand just how pervasive that tracking system is.