I don't know if it's worth it or not. It would depend how you intended to use it. Have you ever seen a game where players can put items in a post box and address them to another player?
In World of Warcraft, the postmaster NPC is a post box, and there are lots of him all over the place. You can post any item, even ones you modified... for PT that would be Aged or Mixed items. You can address it to any other player, and even require them to pay on delivery or return it. When you log in, you get a notification on screen that there is a delivery to collect, and you go to the post box (equivalent of our postmaster) and get your item(s). If they require payment you can check the item first, and if you don't want to pay to receive, or can't afford it you can return it to the sender, free of charge. Or you can leave it at the postmaster until you have acquired the funds.
I think the paid delivery would be too much effort, but being able to post items to clan members who rarely log on during the same times as you (different time zone fe.) would be very nice.
It's not uncommon for the admins to send people letters via the post system either. Because WoW has a generic letter item which can have any text attached to it. Again, that would be hard, but letters can have other items attached, like a present, and sometimes they will send you a post to apologise for downtime or some other negative account maintenance by giving you a free item... Mana? Gold? Sheltom? Jerra? Something nice.

:
I've always wanted to make more use of the post master than regular PT does, and it's not hard to script a web page that admins can send any one, or everyone an item in the post.
It would take modification of the server to implement addressing items to a character, rather than a player account. But since our Warehouse is shared, that's not a major problem. Items with specific statistics would be a very nice touch, if anyone is prepared to put the effort in. ^_^
Effectively, I agree, it's not for the faint hearted. But I think it would be a modification that players could really appreciate if you have the skill and determination.
