According to the National Police Agency on the 25th, letter phishing is a new voice phishing method in which forged mail delivery notices are attached to front doors or mailboxes to prompt victims to call the number themselves. The agency issued an official advisory in April 2025, disclosing the method and prevention guidelines.
The crime unfolds in stages. A scammer posts a forged notice that copies the post office's format at the victim's door, and the victim calls the mail carrier's number listed on it. The scammer who answers poses as a mail carrier and offers another number, saying, "I'll give you the contact information for the person in charge." A second scammer then impersonates an investigative authority, such as a prosecutor at the Seoul Central District Prosecutors' Office, tells the victim, "Your account has been implicated in a crime," and induces the installation of a malicious app to steal cash, gift certificates and virtual assets.
The damage cases are varied and severe. In Seoul, a woman in her 20s was forced to install Telegram and stay on a 24-hour video call, during which she was filmed naked under the pretext of a physical examination. In another confirmed case, a victim was pressured into buying a blank handset without malicious-app blocking features, after which all of the phone's data was stolen.
In December 2024, a case emerged in which scammers impersonated a mail carrier at Incheon's Mansu Complex Post Office to extract addresses and personal information. Earlier, the Gyeongju Police Station arrested and detained members of a voice phishing ring that forged mail delivery notices. Overall voice phishing damage is also rising sharply. According to National Police Agency statistics, voice phishing losses in Seoul soared 2.5-fold in two years, from 160.4 billion won in 2023 to 402.8 billion won in 2025.
There are ways to distinguish a genuine post office notice. Under Article 31 of the Postal Service Act, mail carriers deliver only to the address written on the mail itself, so they never ask recipients for a delivery address. Calling the phone number listed on such a notice is strictly to be avoided.
Anyone who finds such a notice should call the post office's main number directly — not the listed number — to verify its authenticity. Investigative authorities never request app installations or personal information over the phone under any circumstances. Victims or those facing suspicious situations should immediately report them to the National Police Agency's cybercrime reporting system or the Financial Supervisory Service call center (1332).
