Posted: 11th Apr, 2008 By: MarkJ
Several global ISPs, including the UK based
Star Internet, suffered problems with their e-mail servers yesterday after the
Composite Blocking List (CBL), an anti-spam (junk e-mail) organisation, blacklisted IPs belonging to MessageLabs.
Ironically MessageLabs, a well known security services provider, is used by many ISPs to help keep e-mail servers free from viruses and spam. CBL has since rectified the situation and issued a statement:
2008-04-10 CBL Listing Problem:
Commencing at approximately 5AM UTC on 2008-04-10, and lasting as much as 5 hours in some cases, a technical problem in one of our contributory feeds resulted in a number of invalid CBL listings, including some corresponding to servers at a few ISPs and other sites.
The feed was removed from operation as soon as we became aware of the issue and have purged all the IPs it listed in the last 48 hours as a precaution. We have verified that this has taken effect in everything the CBL publishes. Here at the CBL we take false positives extremely seriously, and we do apologize for this issue. We have taken steps to ensure that this cannot happen again in the future.
To further ensure the problem is resolved everywhere, we advise the relatively small number of email administrators who retrieve their copy of the CBL via zone transfer to ensure that they have fetched the CBL at least once after 10:30AM UTC on 2008-04-10 to ensure that the erroneous listings have been purged from their systems. Note that the vast majority of sites use the CBL via direct DNSBL query or zone transfers every 2 hours or less, and thus no action is necessary.
It is not known precisely how the incident came to happen in the first place, although there have been no further reports of any problems.