You'd want "one way" drone delivery mailboxes just like a regular mailbox is one way and must be opened with a key. The package should be dropped on a trapdoor

You'd want "one way" drone delivery mailboxes just like a regular mailbox is one way and must be opened with a key. The package should be dropped on a trapdoor with a locked compartment underneath. It's still vulnerable to theft and vandalism, but it's no different from anything dropped by the mailman.