Status of ybl.megacity.org: DEAD

There once was a DNSBL called ybl.megacity.org. Exactly when it was created is lost to the mists of time, but I'm guessing it was somewhere around the end of 2001 or beginning of 2002, after its maintainer, Derek Balling, parted ways with Yahoo. I recall that the point of the list was to be able to reject mail from Yahoo.

Today, reader John Carver kindly wrote in to let me know that this blocking list is indeed defunct and has "listed the world," installing a wildcard DNS record with the result that if you use ybl.megacity.org in your mail server configuration, you're going to reject 100% of your mail. Query of any domain or IP address under ybl.megacity.org will result in a "127.0.0.2" positive response, that will make a mail server think it should reject the email message in question.

If you use ybl.megacity.org as a DNSBL list in your mail server configuration, I strongly recommend you remove it immediately. The list is long dead, and use of the list will result in you accidentally rejecting 100% of inbound mail.

As recently as 2006, the DNSBL also responded with text warning that it was defunct: "521 The IP is Blacklisted by ybl.megacity.org. This zone has been deprecated for about two years. Maybe if it starts blocking your mail you'll notice and stop using it." This is no longer the case; the text record does not seem to be present.

See also the Ipswitch ImailServer knowledge base article on this topic.