ThunderSub does not collect, store, or transmit any user data. Scan results and your decisions are kept in Thunderbird's local extension storage on your machine only. The extension makes no network requests except the unsubscribe actions you explicitly trigger (an RFC 8058 one-click POST, or opening a sender's unsubscribe page in your browser). No telemetry, no analytics, no third-party services. The "Full Reset" button removes all locally stored data.