Auction house notification
I think the main reason people forgot to claim their stuff in the auction house is that they've forgotten about bidding/setting an auction before. An in-game mail to the player telling the auction a player has hosted/ bid before with the item name included can be sent whenever it has ended would be a good solution to it.
Template: [Item name] you have bid/ hosted in the auction house is now ended. Please check the auction house with /ah to claim the coin/ item.
We've then announced that players will receive their items/coins through deliveries if they did not claim it more than a day.
That can be a solution to have a reminder too, yet, we'll need to request the developer to recode the plugin is not an ideal solution. We do want players to claim the items by themselves as auction shouldn't really need many admins involvement. Only if they have forgotten it will be delivered to their deliveries which deliveries already will have an automated reminder. 😀