An internal shield or hopper-style door allows mail to be dropped in but blocks hands or tools from "fishing" it back out through the slot.
High-quality locking mailboxes, such as those from Mail Boss or Lowe's , typically include several specialized mechanisms to prevent unauthorized access:
Many models use 12-disc wafer locks that are pick-resistant and drill-resistant, often paired with laser-cut keys.
Look for boxes made from 12- to 16-gauge galvanized steel , which provides significant resistance to blunt-force vandalism and environmental wear. Understanding USPS Requirements Mail Boss Locking Security Mailboxes Bundle - Amazon.com