Michael Youngblood
Overview
Alien's Postal Service is a Minecraft mod that adds a working mail system to the game. You place a mailbox, open it, pick a player, and send items. The mailbox itself tells you what is going on: empty, mail waiting, or full.
It ships for Forge, NeoForge, and Fabric on Minecraft 26.2. Grab it from CurseForge or Modrinth.
What it does
Place a mailbox and use it to send and receive items
Search for a player and send from the mailbox UI
Read the flag: down is empty, up is mail waiting, up with a red slot is full
Runs on the client and the server
Technology
One mod, three loaders. Latest release is 1.1.1 (aps-fabric, aps-forge, aps-neoforge for 26.2). Utility & QoL. Client & server.
In game
Mailbox UI — 27-slot box, your inventory, player search, Send:
Three states on the block — empty, waiting, full: