{"success":true,"data":{"id":"no-unsubscribe-bulk-precedence","label":"Bulk mail missing unsubscribe header","description":"Email declares itself bulk/list mail (Precedence: bulk or Precedence: list) but omits the List-Unsubscribe header that CAN-SPAM (15 USC 7704) and RFC 2369 require all commercial bulk senders to include; legitimate ESPs such as Mailchimp, SendGrid, and Klaviyo always inject this header automatically, so its absence on a bulk-precedence email strongly indicates an unauthorised or spam sender.","tier":"warning","category":"header","isThin":false}}