honestly i think no cap is necessary for total listings, why punish someone for accumulating a lot of resources/breeders, but if you guys deemed it necessary i think around 300 would be fair. I think a hard cap on the listing duration would be more effective than anything, Currently we have stuff that's been listed for almost 2 years, i feel like the duration should span 2-4 weeks at most. Right now their are roughly 20,000 pokemon for sale that have been listed for over 30 days, its safe to assume that of those most will never sell at their current price, so a hard cap of 30 days essentially reduces total listings by 40%. I also think that this mail system you are thinking of is way to convoluted and complicated to work successfully, especially for bigger ticket items.Some of the rare shinies have a value of 500m+ which would make it impossible to sell for in game currency, they have to be traded for a combination of other rare shinies/cash/items. I think the only way to buy/sell the bigger ticket items that makes sense is either real time in game or via forums.