Address Not Found Firefox can't

Question

Address Not FoundFirefox can't find the server at us.mc516.mail.yahoo.com.The browser could not find the host server for the provided address. * Did you make a mistake when typing the domain? (e.g. "ww.mozilla.org" instead of "www.mozilla.org") * Are you certain this domain address exists? Its registration may have expired. * Are you unable to browse other sites? Check your network connection and DNS server settings. * Is your computer or network protected by a firewall or proxy? Incorrect settings can interfere with Web browsing.