MailStone for Thunderbird only handles the data strictly required to
add a Bcc address to your outgoing email.

STORED LOCALLY (browser.storage.local, on your machine):
- Your MailStone account email and JWT authentication token, used
to retrieve your folders.
- Your interface language preference and the currently active folder.

SENT TO MAILSTONE SERVERS:
- API calls for login, folder retrieval, and token refresh only.
Email content is never sent by the add-on itself.
- When you certify a message, Thunderbird delivers a copy via the
Bcc address you selected. The MailStone server (covered by the
policy linked below) hashes, timestamps, and blockchain-anchors
that copy.

NEVER COLLECTED:
- No advertising tracking, no profiling, no behavioural analytics.
- No third-party data sharing.
- The blockchain anchor contains a SHA-256 hash, not email content.

Full privacy policy: https://www.mailstone.io/terms#privacy
Support: support@mailstone.fr