I received email saying that an address has been removed and replaced by one I don't recognize.?

Do not answer your password. It could be a phishing scam which is a way to get your password and other information. Take a look at the web address that shows up. Is it a authentic yahoo website? If you have any questions look in the help section for phishing and forward the message to the right people. They will review that and tell you if it is a scam or not. I would also suggest changing your password in case some one has gotten ahold of that.