Postal Service, its employees, infrastructure, and customers by enforcing the laws that defend the United States' mail system from illegal or dangerous use.

[4] As of 2022, there are approximately 1,250 postal inspectors, who are authorized to carry weapons, make arrests, execute federal search warrants, and serve subpoenas.

[3] The Postal Inspection Service has the oldest origins of any federal law enforcement agency in the United States pre-dating the signing of the Declaration of Independence.

Inspectors work closely with U.S. attorneys, other law enforcement agencies, and local prosecutors to investigate postal cases and prepare them for court.

For example, on cases involving international mail, postal inspectors work closely with U.S. Customs and Border Protection (CBP) or U.S. Immigration and Customs Enforcement’s Homeland Security Investigations (HSI); while on domestic mail cases, Inspectors work closely with state and local law enforcement agencies.

The USPIS has responsibility to safeguard over 600,000[10] Postal Service employees and billions of pieces of mail transported globally each year by air, land, rail, and sea.

[15] Chemist Jim Upton from the Inspection Service Crime Lab was the first person to tie the devices to a single bomb maker.

Postal Inspectors, FBI and ATF agents created the UNABOM Task Force, a combination of the words "university" and "airline bomber".

The Postal Inspection Service plays a significant role coordinating and sponsoring training conferences, which are typically attended by several hundred members, drawn from the various sectors mentioned.

[23] The Postal Inspection Service's Internet Covert Operations Program (iCOP) is a surveillance program that monitors social media, cryptocurrency transactions, and USPS internal systems to facilitate "the identification, disruption, and dismantling of individuals and organizations that use the mail or USPS online tools to facilitate black market Internet trade or other illegal activities".

[24] In April 2021, a leaked bulletin labeled "law enforcement sensitive" was distributed through DHS fusion centers and detailed planned protests on March 20 for the World Wide Rally for Freedom and Democracy.

[26] Public exposure of this bulletin raised questions about whether the monitoring of protests and protestors fell under USPIS's area of law enforcement jurisdiction.

[25][27] According to a 2021 USPIS presentation, obtained by Vice Media Motherboard the iCOP Analytics Team's mission is to, "identify and develop intelligence on targets operating on the clear and dark webs for all Inspection Service investigations.

[29] Established in 1981 under the Reagan administration, National Crime Victims’ Rights Week is a federal program led by the Department of Justice (DOJ).

[31] Project Safe Delivery is a crime prevention and law enforcement campaign launched by the United States Postal Service and the Postal Inspection Service in May 2023 that seeks to reduce mail theft and robberies through multiple efforts, including the deployment of high-security blue collection boxes, the installation of electronic locks to replace older locks, law enforcement surges in locations of heightened criminal activity, and other preventive and protective efforts in coordination with federal, state, and local law enforcement.

To strengthen this effort, the Inspection Service also increased monetary rewards for information leading to the arrest and conviction of perpetrators of postal crimes.

For its dedication to protecting children and fighting child exploitation, the United States Department of Justice honored the Postal Inspection Service with its Internet Safety Award.

Launched in 2007, the campaign sought to increase awareness about the schemes, to give consumers valuable information about protecting their assets, and to provide steps they can take to report solicitations.

These segments featured consumer alerts and crime prevention tips covering a wide range of subject matter, including identity theft, mail fraud scams, Internet phishing, and international cross-border schemes.

Postal Inspection Service implemented a program with the North American Precis Syndicate (NAPS) to produce one- and two-column newspaper articles on fraud prevention.

The Postal Inspection Service created the website www.deliveringtrust.com (no longer active) in 2010 to help educate consumers and provide access to resources that allowed them to better protect their privacy and avoid fraud schemes, including those conducted through the mail.

To launch the website, Postmaster General Jack Potter and the Chief Postal Inspector sponsored a tri-fold mailer that went to every delivery point in the U.S.

[citation needed] With an aim to inform and protect as many consumers as possible about current fraud schemes, the Chicago Division of the United States Postal Inspection Service took to the radio waves in 2009 with Don't Fall For It.

Postal Inspection Service partnered with High Noon Production Company to create a series of fraud prevention videos for field inspector presentations.

The show's primary objective over its four seasons was to raise awareness of consumer fraud, educate the target audience about current scams, and provide tips on how they can avoid becoming victims.

During its run, the show received several awards and honors, including: In October 2005, USPIS partnered with the Merchant Risk Council, Monster Worldwide, Inc., Target Corporation, the Federal Bureau of Investigation, and the National White Collar Crime Center's Internet Crime Complaint Center (IC3) to launch the “LooksTooGoodToBeTrue” initiative, an Internet fraud prevention campaign.

In support of the effort, the U.S. Senate passed a resolution, introduced by Senators Carl Levin and Susan Collins, designating the week of August 25, 2002, as “National Fraud Against Senior Citizens Awareness Week.” Chief Postal Inspector Lee Heath joined forces with Postmaster General John E. Potter, Federal Trade Commission Chairman Timothy J. Muris, Assistant Attorney General Michael Chertoff, and representatives of the Royal Canadian Mounted Police to announce the campaign kick-off.

More than 50 press events were held in cities nationwide, supplementing a national multimedia campaign encompassing a wide range of activities: fraud awareness posters were created and posted at more than 38,000 Post Offices across the country; brochures were inserted in Postal Service mailings of stamps and philatelic materials; half-page ads were placed in 40 major metropolitan newspapers; public service announcements featuring Betty White were broadcast on television and radio stations; and fraud awareness flyers were mailed to roughly three million households of seniors and their families.

From July – September, 2005, “Long Shot” — the foreign lottery prevention DVD—was made available through the Postal Store and circulated throughout law enforcement and consumer protection communities.

Funding to print, address, and prepare the mailing for distribution came from money seized by the Postal Inspection Service in a telemarketing fraud case.