Growing up our neighbors wife was a high school teacher. Their mailbox was constantly bashed since we lived out in the country. Neighbor spent weeks building a mailbox out of 3/8 steel, post was a solid steel arbor shaft from something. This thing probably weighed 300 pounds when he was finished but looked identical to an average black mailbox. He set it in about four feet of concrete. Over the next few weeks it got several paint scuffs. Postal inspectors showed up one day, apparently it had broken one kids arm and dislocated another’s shoulder. They threatened to arrest him if he didn’t take it down. He took it down but they never had their mailbox bashed again.