In one case that illustrates the human cost, a Rhode Island man stood in federal court earlier this year and admitted he had used a homemade wire tool to fish envelopes out of USPS collection boxes, stolen the checks inside, chemically erased the payee lines, and rewritten them for far larger amounts. According to the U.S. Attorney’s Office for the District of Rhode Island, the scheme involved tens of thousands of dollars in altered checks. For the individual victims, many of whom were simply mailing rent or utility payments, the first sign of trouble was a bounced payment or an unexplained overdraft weeks after the envelope disappeared. The guilty plea was one case in one state, but the scheme it described has become a nationwide problem: thieves are turning ordinary bill payments into thousands of dollars in fraud losses before victims even realize their mail never arrived.
The crime is called check washing, and by mid-2026 it has drawn formal warnings from the FBI, the Office of the Comptroller of the Currency, and the Treasury Department’s Financial Crimes Enforcement Network (FinCEN). Their collective advice to anyone still dropping paper checks into a blue mailbox is blunt: pay electronically whenever you can, and if you must write a check, use a gel-ink pen.
How check washing actually works
The tools are surprisingly simple. A thief slides a wire hook or a sticky rod through the mail slot of a USPS collection box and pulls out envelopes. Checks inside are soaked in common chemicals, often acetone or household bleach solutions, that dissolve standard ballpoint ink while leaving the printed check stock intact. The thief fills in a new payee name and a higher dollar amount, deposits or cashes the altered check, and moves on to the next box.
In many cases, criminals skip the fishing rod entirely. Two separate audits by the USPS Office of Inspector General found serious weaknesses in how the Postal Service tracks and protects “arrow keys,” the master keys that open collection boxes and cluster mailboxes in residential neighborhoods. The audits covered major postal divisions including Chicago, Houston, Los Angeles, New York, and Washington, D.C., and concluded that compromised keys could be giving thieves direct, no-force access to outgoing mail. A follow-up review found that earlier recommendations to tighten key controls and improve incident tracking had not been fully resolved.
How big the problem has gotten
This is not a scattering of local incidents. FinCEN published a financial trend analysis documenting a sharp rise in suspicious activity reports (SARs) filed by banks. In 2022, financial institutions filed more than 680,000 SARs related to check fraud, nearly double the roughly 350,000 filed in 2021. FinCEN linked much of that surge directly to mail theft. Those remain the most recent national figures publicly available, and no data released since suggests the trend has reversed.
The FBI’s public advisory on mail-related check fraud warns that envelopes left in residential mailboxes with the flag raised, or dropped into collection boxes well before scheduled pickups, are the easiest targets. The bureau urges consumers to hand outgoing mail directly to a postal clerk or use a collection box only close to the posted pickup time.
A Government Accountability Office report (GAO-24-106497) raised a related concern, finding that the Postal Inspection Service’s staffing decisions were not always aligned with the volume of serious crimes against USPS employees and property. If inspection teams are stretched thin in high-theft corridors, cases may go uninvestigated even when victims file complaints, though no agency has publicly confirmed that connection.
What federal agencies say you should do
The OCC’s consumer fraud guidance is specific: use black gel-ink pens for every check you write. Gel ink bonds to paper fibers in a way that resists the chemical solvents thieves rely on, making it far harder to wash a check cleanly. The FBI echoes that advice and adds several layers of protection:
- Pay digitally. Bill pay through your bank, Zelle, Venmo, or direct ACH transfers eliminates the paper check entirely. No paper means nothing to wash.
- Use gel-ink pens. If you must write a check, black gel ink is the single most effective low-cost defense against washing.
- Mail smart. Drop checks at the post office counter or into a collection box just before the posted pickup time. Never leave outgoing mail in an unlocked residential mailbox overnight.
- Sign up for USPS Informed Delivery. This free service emails you scanned images of incoming mail each morning, so you can spot missing items before a thief has time to cash an altered check.
- Act fast if something goes missing. Contact your bank immediately to place a stop payment, file a complaint with the Postal Inspection Service at 877-876-2455 or online at uspis.gov, and file a local police report.
What happens if your check gets washed
Under the Uniform Commercial Code, banks generally bear liability for paying on a fraudulently altered check. In practice, though, the reimbursement process can be slow and contentious. Victims often wait weeks for provisional credits, and disputes over whether the customer exercised “ordinary care” (for example, by using a gel pen or mailing securely) can complicate claims. Knowing your bank’s specific fraud-dispute process before you need it is worth a five-minute phone call, and keeping a record of when and where you mailed a check can strengthen your case if you ever have to file one.
What remains unclear
Several gaps in the public record make it difficult to judge whether the response is keeping pace with the threat. No city-level breakdown of fishing incidents or arrow-key thefts has been released, so consumers cannot compare their local risk to the national picture. The Postal Service has not disclosed a timeline for upgrading collection box locks or rolling out tamper-resistant designs at scale, and the OIG follow-up audit flagged ongoing concerns without detailing specific remediation milestones.
On the prevention side, no published study quantifies exactly how much harder gel ink makes washing compared with standard ballpoint ink in real-world thefts. The recommendation is grounded in ink chemistry and endorsed by law enforcement and banking regulators alike, but outcome data tying gel-ink awareness campaigns to measurable drops in fraud does not yet exist.
A crime that feeds on routine and rewards a simple fix
Check washing thrives on predictability. Millions of Americans still mail paper checks for rent, utilities, insurance premiums, and charitable donations, often dropping them into the same blue box on the same corner at the same time every month. That habit is exactly what thieves count on. The federal evidence assembled so far, from FBI warnings to FinCEN data to a guilty plea in Rhode Island, confirms that the threat is national, growing, and largely preventable. Switching to electronic payments or simply swapping the ballpoint in your desk drawer for a gel pen will not stop organized mail theft, but either step can make your check worthless to the person who steals it.
