All Senders Get Blacklisted, But Smart Ones Manage Risk

There are relatively few things that all marketers seem to agree on, but blacklisting is clearly one. Even industry veterans find them shadowy, secretive, and often frustrating. Last month we conducted a study -- initially to help marketers understand blacklisting -- but the findings also offered practical insight into managing risk while maintaining growth.

It’s important to remember that blacklist operators like Spamhaus think in terms of non-permissioned, unwanted mail and how to help mailbox providers identify its sources. So the only guaranteed way to get around blacklists is to never send unwanted mail -- which means when you don’t have permission to mail subscribers, don’t send them anything. Blacklists aren’t designed to catch or punish marketers, either. Operators don’t care who sends mail or why. Rather, blacklists tend to focus on egregious, black-and-white evidence of spam, not minor infractions or ambiguous signs.

In theory, marketers with sound sending practices should never get blacklisted, but in reality it sometimes happens even to legitimate senders. (We restricted our study to recognized brands, and we still found 20,000 blacklisting events in 2013.) There are many reasons that this could happen, frequently based on the kinds of spam traps used by the blacklists and blacklists’ definitions of sufficient consent.  Spam traps are email accounts that blacklist operators monitor, expecting them to receive no commercial messages. Many spam traps are “recycled” -- abandoned by the original user -- and usually provide hard bounces (“this address is no longer valid”) while they are being “seasoned.” If marketers don’t mail to these addresses for a long time, or forget to remove these bounced addresses, they could eventually send mail to a recycled spam trap. 



In addition, many blacklist operators believe  marketers need to confirm permission by requiring the subscriber to click a link in a subsequent message.  This would prevent typos or malicious signups from adding spam traps to marketers’ lists.

Here’s what we learned about the blacklisting events we studied. First, the variation in the duration of listings and the severity of IPR penalties was remarkable. Only one-in-seven SpamCop blacklistings lasted more than a day, but two-thirds of Spamhaus Block List events lasted more than three days, and more than one-third at least six days. Meanwhile ,inclusion on one Spamhaus list slashed Gmail IPR by almost 60% on average.

It wasn’t a surprise to see blacklisting events increase in the fourth quarter, coinciding with holiday season surges in volume and many retailers’ most important sales opportunity. Taking more risks to maximize reach and revenue in Q4 pays off for some marketers, but those that end up on blacklists get disconnected from their subscribers at the worst possible time. Spikes in blacklisting also showed up within seasons and even weeks: Most Spamhaus Block List events began on Wednesdays, for example.

There were pronounced regional patterns, too. Nearly four out of five Brazilian senders were blacklisted at least once in 2013, while virtually no Japanese senders appeared on blacklists. In North America, roughly one in five North American senders was blacklisted.

Again, these were legitimate businesses, with growth and revenue targets they can’t miss. For these marketers, ceasing to take risks, avoiding new list-building tactics, or not mailing aggressively is not the right response to blacklisting.

Instead, marketers can apply these approaches to understand and manage the risk of being blacklisted:

Use subscriber engagement to drive list hygiene initiatives.  This means monitoring responses to reactivation or win-back campaigns to gauge the difference between inactive subscribers and lost causes. In a recent study, we found that senders often remove inactives too quickly. Nonetheless, the long-gone need to come off your list.

Segment by mailbox provider. When we studied reactivation, we found significantly different tolerances and thresholds for inactives across mailbox providers, and we saw the same thing with their use of blacklists in inbox placement decision-making.  Understand where you can and can’t afford to be aggressive, and remember that deliverability algorithms continually change.

Don’t buy lists. Just don’t. And isolate subscriber sources that are more prone to errors, like point-of-sale address collection. Sources with fewer quality/accuracy screens correlate to blacklist risk, so separating them can accelerate the forensic exercise if you’re blacklisted.

Know your risk profile before you decide how aggressive your program can be. American senders were twice as likely as British senders to get blacklisted in 2013, and all senders were more likely to get blacklisted late in the year. Your holiday campaigns are probably the worst opportunities to take more risks. That’s when your chances of having your delivery disrupted go up, and so do the consequences of losing your connection to consumers.

1 comment about "All Senders Get Blacklisted, But Smart Ones Manage Risk".
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  1. Bill Kaplan from FreshAddress, Inc., March 30, 2015 at 5:46 p.m.

    Good overview of blacklisting with some reasonable recommendations for avoiding the problem in the first place.

    Given the fact that being blacklisted can cost a company in the thousands to millions/week in lost revenues, mitigating the risk of being blacklisted should be first and foremost on every marketer's mind. To this end, following the recommendations above is simply scraping the surface of the problem.

    To properly manage and effectively eliminate the risk of being blacklisted, marketers need to rely on experts in the deliverability industry, which can catch spamtraps/honeypots/other toxic but deliverable addresses before they get into your database, correct hygiene registration errors before you email, and validate the deliverability of each email address in your file. This needs to be done both on the front end (web site, POS, call centers, etc.) as well as on a regular basis to catch formerly good email addresses that get recycled into spam traps.

    For further details on how leading marketers are keeping their email databases safe to send, see

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