Method to find out if someone is logging a conversation on Yahoo Messenger
Solution 1:
In theory, it's impossible to tell, because it's like sending a postcard in the mail: the message is right there and you don't have to do anything to read it if you can intercept it. My suggestion is to install the Off the Record plugin for Pidgin and get your chat partner to do so too, which encrypts your entire chat with a throwaway key so that after the chat the log is unrecoverable.