| |
Challenge-Response
What it means for legitimate email marketers
Challenge-Response overview
Challenge-Response is the latest weapon to be deployed in the never-ending war on spam. Currently, the overall adoption rate of Challenge-Response systems is relatively low. Most forms of Challenge-Response are software-based and deployed at the individual user level. Earthlink is the only major ISP to offer Challenge-Response as a product feature to block spam.
 While the costs associated with spam are high for everyone in the industry, and all have agreed that something needs to be done, Challenge-Response systems have some serious flaws. Unlike other spam-blocking technologies, which operate under a presumption of innocence and block messages if they come from a wrong IP address or contain suspicious characteristics, Challenge-Response systems operate under a presumption of guilt. All email is blocked or filtered, no matter what level of permission the recipient has granted, unless it meets certain criteria for making it into the inbox.
How Challenge-Response works
Challenge-Response systems work by automatically assuming an email sender is suspect unless the sender is in the recipient's address book or is someone with whom the recipient has previously exchanged email. Email from unknown senders are sent a "challenge" requiring a response to a quick visual test that only a human being can complete. Once the correct response is made, all messages from that sender are usually delivered directly to the recipient's inbox. However, Earthlink's Challenge-Response system is more restrictive. It requires the user to take the added step of approving the sender's response. (See below.)
Earthlink spam-blocking techniques
Earthlink has two features to block spam as part of its spamBlocker service.
The first is called "Known spam," which intercepts messages positively identified as spam, and routes them to a special folder. Known spam blocking is turned on by default for all Earthlink users.
To identify spam email, spamBlocker uses a network of specially created email addresses to attract vast quantities of spam. It then analyzes messages that appear to be bulk email for forged headers, invalid unsubscribe information, and other telltale signs of spam.
The second feature is called "Suspect Email" and is a form of Challenge-Response. This feature is optional and turned on by individual Earthlink users. With Suspect Email blocking on, users only receive messages in their inbox from senders who are in their address book. Other messages are classified as "suspect email" and temporarily held in a Suspect Email folder. The senders of those messages (termed "unknown senders") receive an automatic challenge message instructing them how to respond and potentially be added to the address book.
Once a challenge is correctly answered, Earthlink users still need to approve the response before the sender is added to their address book. If declined, all future email from the sender is blocked. If no action is taken or the sender doesn't respond within the time limit, future email is continually challenged. (See the diagram below.)
The Challenge-Response rationale
The logic behind Challenge-Response is that spammers who send billions of unsolicited bulk email will find it physically and financially impossible to respond to the number of challenges they would receive, thus keeping spam emails from ever reaching the inbox. While this may be true, Challenge-Response systems impose an expensive and indiscriminate "tax" on legitimate emailers. They also produce an exceptionally high "false positive" rate, blocking personal email, customer service notices (product confirmations, statements) as well as permission-based messages from legitimate marketers whose mail consumers have previously consented to receive.
What Digital Impact is doing
While Challenge-Response may have a role in filtering questionable email on a case basis, Digital Impact believes that use of such systems as a primary form of spam filtering is dangerous to email as an effective communications medium, both commercial and personal. We believe the best way to control spam is to authenticate email from legitimate mailers (and their agents) and certify their compliance to industry best practices, while respecting both consumer privacy and permission in the process.
Over time, we believe that the appeal of Challenge-Response will wane as consumers become aware of its flaws and other, more responsible forms of spam filtering take hold. In the meantime, Digital Impact is closely monitoring developments in the Challenge-Response arena, particularly at Earthlink, and taking steps to minimize their potential impact.
To date, Challenge-Responses from Earthlink average about .75% of the total email sent to the Earthlink domains, or about 10-15 daily challenges per client. But Earthlink is heavily promoting its Challenge-Response feature and has projected about 50% adoption by its member base by year-end, so the potential impact could significantly grow over upcoming months.
Rather than ignore Challenge-Response as others have chosen to do, on July 1st, Digital Impact began to manually process Earthlink challenges on behalf of its clients at no charge. We will continue this service for the near-term as we monitor growth in the Challenge-Response category and investigate more permanent solutions. If responding to Earthlink challenges becomes cost-prohibitive, Digital Impact may offer response processing to clients on a fee basis. Additionally, we are evaluating ways to intercept and process other forms of Challenge-Response for our clients.
What you can do
As a legitimate email marketer, there are a number of things you can do to address the Challenge-Response issue.
- Let your voice be heard. If you agree with Digital Impact's position, tell the management of Earthlink what you think of their use of Challenge-Response (1-800-395-8425 or 404-815-0770). The opinions of Earthlink's advertising partners may carry particular clout.
- Educate your customers. Tell your customers - especially those with Earthlink accounts - about the flaws of Challenge-Response and how it could interfere with their receipt of your messages and special offers. Contact Digital Impact's Deliverability Team at deliverability@digitalimpact.com for additional information and strategies.
 Pursue "add to address book" strategies. Suggest that customers add your sending domain to their address books at the time of data capture and within your subscription management pages. Periodically remind them in your subsequent email messages. Getting into customer address books is your best counter to Challenge-Response as well as other forms of filtering. It virtually guarantees the receipt and favorable placement of your email.
- Seek alternative email addresses. If you find that your open and click rates are slipping at Earthlink or other domains, solicit alternate email addresses from your customers. Again, you can do so at the time of data capture and within your subscription management pages, and Digital Impact is prepared to help.
Learn more about Challenge-Response
For additional information on Challenge-Response, we recommend you checkout the following:
EarthLink to Roll Out Challenge-Response, Rich Media Blocker
Critics challenge anti-spam system
Responding to Another E-Mail Challenge
Earthlink's FAQ
|
