People in Northampton have been warned to look out for signs of fake letterboxes that can be attached to front doors by thieves.
The letterboxes can be attached over the real opening then detached later after the postman has made his delivery.
Fraudsters return and take all the mail without being detected then sift through for anything that may contain personal details.
A spokeswoman for Northamptonshire Police said: “We’d ask people to keep their eyes open for any sign their door or letterbox has been tampered with.”
The warning comes after the National Fraud Intelligence Bureau (NFIB) noticed an increase in reports of the scam.
The mail is sometimes used to open various lines of credit with financial providers in the name of the innocent person.
However, fraudsters will periodically remove the item, which may leave noticeable markings.
A spokesman for the NFIB said: “Be vigilant and check for any suspicious activity, tampering of your post or letterbox or for suspicious glue markings on the wall.
“Check all post received from financial institutions, even if it appears unsolicited.
“Consider reporting theft of mail to your local police force and any cases of identity fraud to Action Fraud.”
Anyone who has been a victim of identity fraud can use Cifas Protection Registration (https://www.cifas.org.uk/protective_registration_form)
If you, or anyone you know, has been affected by this fraud or any other scam, you can report it to Action Fraud by calling 0300 123 2040 or visiting www.actionfraud.police.uk.