These schematics require Ars Nouveau to function properly (version 4.12.6 was the one used). This is a mail system designed to function regardless of distance or dimension in your multiplayer world. You will need to bind a series of stabilized warp scrolls to specific location to activate the portals necessary. You will also need a filled Source jar in order to initially activate these portals. 

The portal attached to the outbox of the mailbox should always lead to the conveyor belt leading into the Frogport that is higher than the others. The portals in the hub should lead to the inbox conveyor belt on your recipient's mailbox, with the rest of the frogports being named after the different recipients. 

I reccomend building the hub close to spawn so the chunks remain loaded. If that is not possible, or you do not have means to keep the chunk loaded, you should expect longer delivery times. To use, simply put the items you want to send (up to nine stacks) in the chest, rename the sign to list the recipient's name, then hit the stone button to send the package off.