Well, when transport usual cargos the route stations look like the image below.Pick up cargo on one island, the unload button become clickable, then unload where ever you want.I like to deliever basic needs and some common construction materials from one major production island and to every island who comsume them in the same session.You can see like the clay in this route, unload button is clickable which means i can unload them on ever island.
Same as mails, produce in a major population islands and deliver them to small islands.However current mail route system are different.When i load some mails from one island,System force you to unload them at the next island, and i cant unload them in another island,all the unload button is unclickable, the only way to unload them is let the system do it.I cant even adjust their number, the only thing i can control is where to load and how many to load.
This doesnt make sense, if i have 5 island and A is the major population island, BCDE is small island, and i want to load mail from major island and deliver them to other small island, for now i can only do this in two way
1 make 4 different ships to deliver mails for every single island, AB AC AD AE
2 let one big ship deliver them but the ship have to do route like:ABACADAE, which make route much more complex and harder to control.
It can be more simple if systems just let me decide where to unload.
Besides, i know the reason might be the computer hardly know where the mails comes from if we can load them freely.I suggest it will be more easy to lock the load buttons where every mails in slots can only load from one island.When the airship unload mails the program just need to read where the mails in the slots load and decide what it will become.