Fear Spreading that Challenge-Response Email Filtering May Wreak Havoc
Recently, large internet service providers have been working on challenge-response systems that ask the sender of an email message to answer some sort of question or interact with a web application before email will be delivered to a protected email address. Many journalists expect that a huge number of disparate systems, all performing the same basic task, will be deployed in the near future.
On CNET News.com, Declan McCollough predicts that challenge-response systems will wreak havoc on list servers and other legitimate forms of communication. According to the article:
Challenge-response systems, ironically, share some characteristics with spam: In small quantities, both are only mildly annoying to the recipient. But as quantities increase, they make it more difficult to use e-mail at all. MailFrontier.net is a good example: It prevents its users from signing up to mailing lists unless the list operator manually intervenes to answer the challenge, a process that is exactly backward.
We agree. As soon as we can, CTDATA will notify subscribers to our websites' headline services that we will unsubscribe anyone whose mailbox automatically challenges email from our sites.
Our users opted into receiving these emails, and it makes no sense for challenge-response systems to invalidate all of the decisions that email users previously made on well designed and well behaved Internet communications systems.