Cisco antispam tool blocks thousands of emails following domain registration blunder

Spam messages
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A blunder involving Cisco’s SpamCop anti-spam service resulted in thousands of emails being blocked after being mistakenly labeled as spam. The issue occurred after SpamCop allowed its domain to expire, resulting in mail servers that employed the service to automatically reject any outgoing messages.

As a result of the domain expiration, thousands of organizations and mail administrators all over the world found that their outgoing emails were listed as spam, blacklisted at 

Administrators were also confronted with the following, rather unhelpful, message when they reviewed their mail server logs: "The error on is: An error occurred while processing your request."

Once SpamCop’s domain expired, visiting resulted in a redirect to a domain parking service’s IP address. This meant that every time SpamCop checked for a valid DNS entry to see if an IP address has been associated with spam in the past, it returned a positive result – blocking the message.

Worryingly though, whoever re-registered the domain name again with the domain registrar only chose to do it for one year. Which means that the issue might come back to bite users in 2022.

Remember to renew

Cisco did act quickly to resolve the issue by renewing the expired domain. This should have fixed the problem for email administrators but some were still reporting issues. It seems that how quickly email services return to normal can vary significantly.

If organizations continue to receive error messages, it is possible that the problems are caused by cached DNS lookup results stored on local DNS servers. They could try deleting the cache, which should return functionality to the SpamCop service.

Allowing a domain to expire is an embarrassing reason for disruption to occur – and easily avoided. Businesses could set up a master spreadsheet of all their domain names and renewal dates or, where possible, pay for critical domains to renew automatically.

Via Bleeping Computer

Barclay Ballard

Barclay has been writing about technology for a decade, starting out as a freelancer with ITProPortal covering everything from London’s start-up scene to comparisons of the best cloud storage services.  After that, he spent some time as the managing editor of an online outlet focusing on cloud computing, furthering his interest in virtualization, Big Data, and the Internet of Things.