I'd think instead of sending the messages ingame it should perhaps send it to you on the forum. That way it doesn't have to connect with the server and it can give you more information than if it sent you a /mail or a /msg.
That way the message could be detailed and specify exactly what the item was since it wouldn't have a character limit, such as
"The Efficiency 4 Unbreaking 2 Fortune 1 Diamond Pick from mrfloris that you bid on was outbid by 32,000Noobz"