This is a soluton for the gilseller problem:
Why not limit the amount of gil a player can send via the delivery system. This featur alone would severely hinder gilselling operations. It would force the gilselling to take place in trade in person. This means a player would have to not only buy the gil but setup meating times to meet with the representative from the gilselling company firsthand.
This cap on the amount sent via delivery would seem like a very minor inconvinience in order to put a huge limit to the amount of gil a company could sell. I think a 500k limit on sent gil is resonable. And I also propose a limit to the max gil sent in a week to other characters. I'm looking for ppl's opinions on this.
Also I think sending gil to and from mules should be completely exempt from the cap.