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What You Need to Know About Confirmed Opt-In (COI), Mistyped Email Addresses, and Typotraps

Craig Swerdloff Archive

There has been a lot of talk recently about Spamhaus' listing of several well-known brand retailers in their Spamhaus Block List (SBL). These listings are part of Spamhaus efforts to encourage email marketers to use a Confirmed Opt-In (COI) permission strategy. We would like to share what we know about their position, reactions from the email marketing community, and how this informs our own efforts to support marketers with data-collection best practices.

First, a little background: Since 1998, the Spamhaus Project has worked with law enforcement and email receivers (ISPs) to identify and stop spammers, and is now one of the foremost anti-spam organizations in the world. One can debate their policies or their methods, but not their mission. Spam is a crime. It wastes resources, clogs inboxes, and reduces the effectiveness of email marketing for the rest of us. Therefore, we applaud Spamhaus for their mission.

From the very beginning, Spamhaus has advocated Confirmed Opt-In (COI) as a best practice. The defining feature of COI is that unless a new subscriber follows a confirmation link emailed to their address, the marketer will not send them any additional mail. Spamhaus advocates COI because it makes it much more difficult for someone to sign themselves or others up for email they do not actually wish to receive. You can read more about Spamhaus' position on COI here.

As part of this effort, Spamhaus has recently started warning non-COI marketers by flagging them in the SBL when they are seen sending multiple emails to “typotraps.” These are addresses at slight variations of popular email domains (examples might include, or that are monitored by Spamhaus. Because no confirmation links sent to these addresses are ever followed, any subsequent messages demonstrate the marketer is not using COI. So far, Spamhaus has only been flagging these senders, but they have made it clear that blocking will ensue if they do not move to COI.

Many email marketers face challenges in moving to COI. Perhaps most significantly, it is not uncommon to see a percentage-point reduction in net, new registrations as high as the low-to-mid, double digits. Steve Linford, CEO of Spamhaus, acknowledges this in his recent interview with Ken Magill. He goes on to explain five factors contributing to this drop:

“While it's true that COI has a drop-off rate during confirmation, I would argue that the drop-off rates you see are due quite simply to logical reasons: (1) User has entered a bad address and did not get your COI request. (2) User was not really that interested and having had a minute to "cool off" has now decided not to subscribe. (3) User actually couldn't give a damn, did you really want them that badly? They'd probably have pressed the "this is spam" button later. (4) User gave someone else's address and that recipient chose not to confirm. (5) Your COI request arrived looking like just another advert to press delete on.”

Presumably, other factors, such as delayed delivery of confirmation messages, are also significantly to blame, but Mr. Linford's points remain valid. The challenge for marketers wishing to employ COI is the same as for those using Single Opt-In (SOI): ensuring that people who want to hear from you do hear from you.

At Experian Data Quality, we see our role as supporting marketers in their efforts to optimally grow their subscriber base. Part of doing so is identifying mistyped email addresses at the point of collection and thereby allowing potential subscribers to make corrections. This tactic directly addresses the first, and perhaps most common cause of low COI rates identified by Mr. Linford: a user enters a bad address and does not receive their confirmation message.

Here are a few data points from Q4, 2012 to consider:

  • Across our customer base, the average rate of invalid email addresses collected was 6.98%.
  • When prompted to reenter a valid email address, people did so an astounding 68% of the time.
  • The result was a drop in the net invalid rate to 2.23%, and a corresponding increase in the number of valid, net leads.

These numbers support the case that Experian Data Quality's email validation service is highly complementary to a COI permission strategy, optimizing subscriber growth while minimizing the negative effect on signup rate. If you are a marketer and are interested in testing our service at the point of data collection, please contact us about a free trial.