Carl’s SEO & Web Design Blog

One of our clients recently complained that suddenly they couldn’t send any email. Their outgoing email (SMTP) was through Comcast, and it was being was filtered with a spam filter. The commercial black list used for that had their IP listed as a spamming IP and blocking their outgoing email. Their outgoing IP belonged to Comcast.

Comcast uses dynamic IP addressing by default. About once a week, they tell me, the IP is reset. Normally, it’s reset to the same value. About once a month, however, it is reset to a new IP. The new IP he got was black listed as a spamming IP.

Comcast has a serious problem with this. On our own black list at:
http://www.creatingnewworlds.org/stopspam.cfm
we list several Comcast IPs that have spammed us. This list is public, and goes to hackers with our encouragement. These incoming emails are illegal. We notify Comcast on their abuse email at the current time when this happens, but so far they have not replied except with an auto-reply and they seem to have no concern about clearing any listing here. The resulting IPs would be unstable along with their host system because we encourage hackers to use this list for their development and nuking.

If you wish to see if your own IP is listed on the commercial black lists, you can check:
http://rbls.org

Just remember - if you are using Comcast, you have no assurance that the IP they roll into you is clean. If you have your own host for email and use Comcast for SMTP, you should be sure your host has a good spam filter (using a commercial black list) and can protect you.

This entry was posted on Thursday, June 1st, 2006 at 9:16 am and is filed under Web Design, Spam. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.