With all the U.S. government surveillance of electronic communications that's come to light over the past year, you might be tempted to think that good-old-fashioned snail mail offers a safe alternative. You'd be wrong.

A New York Times report published today shows that the U.S. Postal Service monitored nearly 50,000 packages sent in the U.S. in 2013 through a program called "mail covers." The surveillance program, which allows law enforcement agencies to access mailing and return addresses—anything written on the outside of a package—before it is delivered, has been in place for over a century, the Times reports. The scope of its use was revealed in an audit published by the Postal Service inspector general's office in May (and covered by Politico in June) and through documents the Times obtained via Freedom of Information Law.

The audit showed that mail covers were much more widely than previously reported, and expressed worries over privacy and the Postal Service's ability to effectively conduct its own surveillance:

In addition to raising privacy concerns, the audit questioned the efficiency and accuracy of the Postal Service in handling the requests. Many requests were not processed in time, the audit said, and computer errors caused the same tracking number to be assigned to different surveillance requests.

"Insufficient controls could hinder the Postal Inspection Service's ability to conduct effective investigations, lead to public concerns over privacy of mail and harm the Postal Service's brand," the audit concluded.

And lest anyone believe that all of the tracking was done for legitimate law enforcement reasons, Arizona's Sheriff Joe Arpaio makes a cameo to prove us wrong.

In Arizona in 2011, Mary Rose Wilcox, a Maricopa County supervisor, discovered that her mail was being monitored by the county's sheriff, Joe Arpaio. Ms. Wilcox had been a frequent critic of Mr. Arpaio, objecting to what she considered the targeting of Hispanics in his immigration sweeps.

The Postal Service had granted an earlier request from Mr. Arpaio and Andrew Thomas, who was then the county attorney, to track Ms. Wilcox's personal and business mail.

Using information gleaned from letters and packages sent to Ms. Wilcox and her husband, Mr. Arpaio and Mr. Thomas obtained warrants for banking and other information about two restaurants the couple owned. The sheriff's office also raided a company that hired Ms. Wilcox to provide concessions at the local airport.

Fortunately, much like the NSA's metadata collection, mail covers allow law enforcement to record where a package is going and from where it came, but not what's actually inside. For that, they still need a warrant.

[Image via AP]