{"success":true,"data":{"id":"empty-from-header","label":"Empty or missing From header — no legitimate sender produces this shape","description":"From header is missing, empty, whitespace-only, or contains an empty angle-bracketed address like `<>`. Every legitimate email has a populated From address — Gmail/Outlook/Apple Mail all reject or normalise messages with missing senders, and no legitimate newsletter platform or transactional email provider ships such a message. Empty or whitespace-only From is either a header-parsing glitch (rare in practice) or a deliberate attempt to slip past substring-match whitelists and sender-based scoring that expects a real address.","tier":"warning","category":"sender","isThin":false}}