The Mail in Sync Firefox extension accesses a user's Mail in Sync account using the session cookie established when they signed in to mailinsync.app in their browser. No additional data is collected, stored, or transmitted by the extension itself. The extension reads the user's sync statistics and can trigger an immediate sync — both actions are subject to the same data practices described in this policy. The extension does not operate independently of the user's Mail in Sync account and collects no data when they are not signed in.

For more information, refer to: https://mailinsync.app/privacy