I'm not sure if a post has been made about this before or not, but I have a few ideas that I think could be introduced with the Auction. It is possible, because it sends you mail in game when you get outbid in Auction.
First Idea, Have Auction send you mail In-Game when you successfully sell an auction.
So, if I were to put 16 diamonds up for 16k buyout. And Miner_man123456 were to buy them out, I'd get a mail In-Game telling me that Miner_man123456 bought out 16 diamonds for 16k from me. This would be a great investment idea as well. You could know who bought your items, so you can make more Player-to-Player trades and sales.
Second Idea, Have Auction send you mail In-Game when you win a bid at auction.
So, If I had the highest bid on an auction, and the time runs out, I win. but, it would also send me mail In-Game telling me that "I won the Auction for 16 diamonds with a bid of 15,468 Noobz." It would be great and I'm sure many players would appreciate this so they know when they can collect their items etc.
Thanks for considering my suggestions and ideas,
nebih