Indeed [1] "Computer security and information privacy expert Bruce Schneier compared MICT to the mass surveillance of the National Security Agency (NSA), revealed in June 2013 by Edward Snowden. Schneier said, "Basically, [the USPS is] doing the same thing as the [NSA] programs, collecting the information on the outside of your mail, the metadata, if you will, of names, addresses, return addresses and postmark locations, which gives the government a pretty good map of your contacts, even if they aren't reading the contents."
The information was provided to the USPS, not law enforcement. That's why law enforcement needs to request the info via USPS. USPS is not snooping, but since law enforcement is not in the business of delivering the mail, that information has not been provided to them by the sender and is snooping. Same thing either digital metadata - parties exchange data, provider needs basic info to send, government captures info eventhough they aren't involved in the business of providing those services.
USPS' law enforcement division is absolutely doing active searches, and even investigations outside, above and beyond anything to do with mail. It's kind of wild.
