If the addresses are correct, there is not much you can do. Comcast name servers have marked the address or the entire domian as invalid. Comcast support has no idea how to fix this issue and usually the name servers are automatically refreshed and the problem goes away for a while.
Customer Security Assurance Department The Customer Security Assurance organization is here to help you have a safe and secure online experience. This dedicated group of security professionals responds to issues pertaining to phishing, spam, infected PCs (commonly referred to as "bots"), online fraud and other security issues. Business Hours: 6:00am – 2:00am EST 7 days a week Contact: (888) 565-4329
Need Email Help? Please post the following information in your post. Do you use XfinityConnect? The Full or Lite version? Do you use an email client? Which one? (Eg; Windows Live mail, Outlook, a smartphone etc.) Which browser/version do you use? And- have you cleared your browser cache? Which operating system? XP, Vista, Windows 7, Mac OS X Details of the problem you are having.