Mail Transaction
Players can trade via mails. Once the player attached a file, tick the "C.O.D" box, enter the number of coins, set the email returning time and send the mail, then the receipient needs to pay the required money after receiving the email to get the item .
The coins the receipient paid will be send back to the sender via mail; if the receiver has not paid for the items in the email, the email will be returned to the sender after the appointed returning time. And bounded items can not be transacted.