Why do I receivie an error message when I try to send email from my comcast webmail?

If you've received the below error message when trying to send outgoing e-mail, it is possible your computer is infected with a virus. You therefore will need to take immediate actions to clean and protect your computer. The error message reads as follows: 550 IP blocked by ldap:ou=rbl,dc=comcast,dc=net -> 550 Message sending error. Please go to http://faq.comcast.net/faq/answer.jsp?name=17867&cat=Security&subcategory=Spam Comcast's security experts have observed a recent increase in spamming exploits - specifically, attempts by spammers to hijack and use unprotected or infected computers to deliver their spam. The spammers' intent is to disguise their own identities - and they can accomplish these attacks without the knowledge of the computer owner Therefore, if you received one of these e-mail error messages, it's likely that your computer could possibly be being used by these spammers. Comcast has made it a priority to thwart these attacks - and as part of our ongoing efforts to protect our customers and our network, we are temporarily (for a period of 24 hours) suspending e-mail accounts on any infected customers generating abnormally high outbound e-mail traffic. Doing so will give our customers notification about the situation, so they can adequately protect and repair their computers. Below there is a four-step process that comcast strongly advise following in order to stop this unauthorized access to your computer. In addition to protecting your computer against these spammers, these are smart steps to take in general towards ensuring the overall safety and security of your computer. 1. Visit http://www.microsoft.com/security/ - and make sure that you have the latest patches and updates from Microsoft. 2. Install a personal firewall. Note: you can go to the Security Center section of the Comcast portal to take advantage of the free firewall offer from McAfee. 3. Purchase or update Anti-Virus software - go to http://www.mcafee.com for additional information. 4. Have your computer professionally cleaned at your local computer or electronics retailer. During the 24-hour period when you will be unable to send e-mail using programs such as Outlook Express, you can still use Comcast Webmail to send messages. To access Comcast Webmail, click the Mail button from the Comcast.net start page located at http://www.comcast.net. If you are certain that your PC is not infected with a virus, and you send out a large number of legitimate, requested e-mail messages per day, please contact mymessageisnotspam@comcast.net. Include your reason for sending a high volume of e-mail messages (news letter, mailing list etc.), the number of recipients that have requested to receive your e-mail, and the address that you're sending e-mail from.