JapanWhat is sender information disclosure procedure?
The sender information disclosure procedure in Japan is a legal process under the Act on Regulation of Transmission of Specified Electronic Mail that allows recipients of unsolicited commercial emails to request and obtain the sender’s name, address, and contact details.
What the Law Says
The Act on Regulation of Transmission of Specified Electronic Mail (commonly called the 'Spam Email Act') establishes mandatory sender identification and a formal procedure for recipients to request disclosure of sender information.
Under Japanese law, businesses sending commercial electronic mail (e.g., promotional emails) must clearly display their name, address, and contact information in every message. If this information is missing or false, the recipient may submit a formal request for disclosure.
The sender must respond within 48 hours of receiving the request — either by disclosing the required information or explaining why disclosure is not possible (e.g., technical error). The sender may charge up to ¥3,000 to cover administrative costs, but must notify the requester in advance.
Senders are required to retain records of email transmissions — including sender identification data — for at least 7 days after transmission. This ensures traceability and supports enforcement of disclosure obligations.
Statutory TextThe sender of specified electronic mail shall, upon receipt of a request from the addressee, disclose without delay the name, address and telephone number of the sender.
— Act on Regulation of Transmission of Specified Electronic Mail, Art. 20 — Disclosure of Sender Information
Statutory TextThe sender shall respond to the request within forty-eight hours from the time of its receipt.
— Act on Regulation of Transmission of Specified Electronic Mail, Art. 20, Paragraph 2
Statutory TextThe sender may charge a fee not exceeding thirty thousand yen for the cost incurred in responding to the request.
— Act on Regulation of Transmission of Specified Electronic Mail, Art. 20, Paragraph 3
What to Do
Confirm the email lacks valid sender identification (name, address, phone number).
Send a written request (by email only) to the sender’s listed or inferred contact address.
Include your name, email address, date/time of receipt, and subject line of the original email.
Wait up to 48 hours for a response; if none is received, file a complaint with the Consumer Affairs Agency or Ministry of Internal Affairs and Communications.
Sources
Not legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-06-08.