Archived chats are limited to 100 transactions or to 20 minutes of chat - A transaction is counted each time a user sends a new conversation line or hits Return on Messenger.
Chat through instant messages
Are you chatting with someone on an older version of Yahoo Messenger? Certain features won't work when chatting with someone who is does not have the latest version of Yahoo Messenger.
Messenger conversations are fun and very easy. We'll show you how to start them and stop them.
This article explains why you might sometimes receive what appear to be chat messages in Yahoo Mail.
Limit for conversations . Maximum conversations allowed in Yahoo Messenger. You may have up to 100 separate conversations at the same time.