LetterAgent
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Check washing is mail theft with chemistry: criminals steal outgoing checks from home mailboxes or blue collection boxes, then use solvents to erase the ink and rewrite the payee and amount. The victim's signature stays intact, which is what makes the altered check convincing. Gel-ink pens resist the solvents because the ink bonds with paper fibers, and handing checks directly to a postal clerk skips the riskiest step.
It starts with theft. Criminals take outgoing mail from residential mailboxes with the flag up, pry open blue USPS collection boxes, or steal from apartment mail areas. They are looking for envelopes that feel like checks: bill payments, rent, contractor deposits.
Then comes the washing. Common household solvents, things like acetone and nail polish remover, dissolve most ballpoint and rollerball inks while leaving the paper intact. The thief erases the payee name and the amount, then writes in a new payee and a much larger figure. Your genuine signature remains at the bottom, untouched, which is why the fraud passes casual inspection at the bank. Some operations are sophisticated enough to alter the memo line and forge endorsements on the back.
The single cheapest defense is the pen. Gel pens with pigment-based ink soak into the paper fibers rather than sitting on the surface, which makes them far harder to wash off than standard ballpoint ink. Write checks only with such a pen, and fill every line completely: draw a line through empty space on the payee and amount lines so nothing can be added later.
The second defense is how the check enters the mail stream. USPS itself advises against dropping checks in blue collection boxes, especially after the last pickup of the day, when they sit overnight. Hand the envelope to a clerk inside the post office, or drop it in the lobby slot. At home, do not leave outgoing mail in the box with the flag up for hours: bring it to the post office if you can.
Third, collect your incoming mail promptly and watch your accounts. The faster you spot a check that never arrived or an amount that changed, the faster your bank can act. Many banks let you set alerts for checks above a threshold, which is worth turning on if you still write them.
Contact your bank immediately and request a stop payment, then close or monitor the affected account. File a report with local police and with the US Postal Inspection Service, which investigates mail theft and check fraud specifically. Keep copies of everything: the police report number, the bank's fraud case number, and any images of the altered check your bank provides. In Canada, report to local police and the Canadian Anti-Fraud Centre, and notify your bank the same way.
For recurring bills, your bank's online bill-pay service sends either an electronic payment or a bank-issued check, and the bank's check carries protections your personal check does not. For one-off payments, money orders and cashier's checks are harder to alter and easier to trace. Businesses that still issue many checks often use "positive pay," a bank service that matches every presented check against a list of issued checks and flags anything altered.
This is general information, not legal advice.
| Protection | Why it helps | Effort |
|---|---|---|
| Gel or pigment-ink pen, lines filled completely | Ink bonds with paper fibers and resists solvents; no blank space to alter | Buy the right pen once |
| Hand checks to a clerk or use the lobby slot | Skips the blue box and the home mailbox, the two most common theft points | A trip to the post office |
| Collect mail promptly, set bank alerts | Shrinks the window between theft and discovery | A few minutes of setup |
| Stop payment and fraud reports if compromised | Limits losses and creates an official record | Phone calls and forms, done fast |
| Bank bill pay or money orders instead | Removes your personal check from the mail entirely | One-time switch per payee |
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LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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