What do I do with the message ‘Unknown user or wrong password’?

This message is often given when the SSL is disabled in the browser. SSL is a way of encrypting so that a secure connection can be made between the mail server and the browser. Always check whether this is enabled in the browser and enable it if it is not. After that, Yahoo webmail is easy to use. You can log in, but there are still problems with opening or sending e-mail. Then check whether the connection is via proxy and turn it off.