Men who scour St. Louis streets for prostitutes can reportedly expect a special delivery from police: bright yellow postcards sent to their homes offering a reminder of sexually transmitted diseases along with their court date.

In an effort to curb prostitution, St. Louis police are targeting the “johns” who solicit prostitutes in hopes to deter residents from the crime, which is an ordinance violation carrying a penalty often no harsher than a fine, the St. Louis Post-Dispatch reports.

“If there weren’t customers, prostitutes would be out of business,” St. Louis Police Capt. Dan Howard told the newspaper. “And what we’re looking to do is put them out of business.”

The program will be rolled out this week in two neighborhoods – Carondelet and Holly Hills – where residents have complained of prostitutes trolling for customers.

Police tried the same tactic in 2005 when authorities noticed prostitution cases soaring citywide. Similar campaigns have also been used in cities from Sarasota, Fla., to Baltimore, Md., to Oakland, Calif., the newspaper reports.