Email system restoring recipient identifier based on identifier-for-disclosure for establishing communication between sender and recipient

摘要

A recipient identifier and communication condition information stored in a recipient-identifier storing unit are encrypted by an identifier-for-disclosure creating unit of a recipient terminal to create an identifier-for-disclosure. An identifier-for-disclosure notifying unit notifies a sender terminal of the identifier-for-disclosure. When a communication request using the identifier-for-disclosure is sent from the recipient terminal, a restoring unit of a relay system extracts the communication condition information from the identifier-for-disclosure. Only when communication conditions included in the communication condition information are satisfied, communication between the recipient terminal and the sender terminal is established.