There should be a set of options that you can click on the map. Like on the side, some check-boxes that would allow you to make the houses, towns, signs, etc... show up that you placed.
So if you click town names, signs, and houses, only they will show up on the map. It is to make the map less crowded.
But anyway, back onto this topic. Mabey aside from the tabs you can switch the map so that it shows the dynamic things on the island, like houses, mabey even cannons. That way it would be easier for the postman to deliver the mail.
But who says the postman has to deliver it? Mabey on letters you can assign a particular kingdom for it to go to when you put it in the mail box of any postoffice on main and other kingdom islands. Then the letter is sent to the kingdom, and from there, it is sent to the account name assigned to the letter by a npc.
