Forestry: CE - Mail

Players write letters, attach messages and item stacks, and address them with stamps before dropping them into a mailbox. Letters come in several tiers with different costs, and packmakers can set individual mailing costs for specific items through datapacks. Stamps are required to send letters, and the number of stamps grows with the number of items and the tier chosen. Letters can also carry images and GIFs, which the author describes as a way to communicate more playfully.

The addon adds PO boxes that hold inventories and separate private inboxes, so players can receive mail without sharing a mailbox. The mail system can also be used by autonomous item transport. A Trade Station lets players sell items through the mail: a seller names an item, sets its price, and players buy it by selecting the station in a UI. A Catalog book lists the active Trade Stations. Forestry: CE - Mail requires Forestry, and it is open source under the GNU Lesser General Public License v3.0 only. Servers that run it need every player to install it too. Files are published for NeoForge 1.21.1, with 3.0.0-alpha6 as the latest file.