Thanks to @SmallJoker AKA Krock for helping me with the minetest.swap_node part of the mod!
This repository is the continuation of everamzah's
mailbox mod for Minetest.
It provides a modified xdecor mailbox, enhanced to be able to accept books-only as an option (blue box) or the default accept-anything (red box).
Releases are available on the releases tab (GitHub)