Service of income-tax communications through specified physical and electronic addresses is governed by prescribed address and security rules. Service of notices, summonses, requisitions, orders and other communications under section 501 must be made only to the addresses specified for physical or electronic transmission. The rule recognises PAN records, return addresses, prescribed forms, company registered-office details, government and utility records, and correspondence records, while also allowing a different address furnished in writing to the income-tax authority. For electronic communication, the rule similarly identifies permitted email and registered mail addresses. The systems authorities must prescribe secure transmission procedures, formats and standards, and maintain security, archival and retrieval policies.