If you don’t want to use Voice Chat and just want to make a text messages (including sending “a lot of messages” that can be categorized as chat room spam messages–not recommend doing like this though) you can use this simple and small Yahoo Messenger Chat Client called Y Vampire Chat. Because this client seems designed to use in Chat Room, we strongly suggest you to use this Yclient only when you are a Rooomer or want to join Chat Room.
Features in this Y-Vampire-Chat (Public version)
Emoticons, Room Option: Room Lagger, Lagger2, Boot Option, Room List, and many more
Download Free Y Vampir Chat
You can download those chat client from the links below: