{"id":"email-service-single-folder-per-user","text":"A message can only exist in one folder per user; `move_to_folder` removes from the source before adding to the target.","truth_value":"IN","source":"entries/2026/06/05/distributed-email-service-email_service.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"email-service-single-folder-per-user","truth_value":"IN","reason":"premise"}]}}