Block Lists Can’t Guarantee the Inventory You Want

On their own, block lists are too blunt of a tool to protect you from buying unwanted inventory. Advertisers who want more precision in their programmatic campaigns need a proactive, continual approach — not a single “set-it-and-forget-it” solution.

Programmatic offers advertisers the ability to purchase ad space at scale, but ensuring quality inventory remains a challenge. To avoid wasting spend on unwanted ad space, many advertisers rely on block lists — indexes of websites, apps and/or categories they have no interest in advertising on.

But when it comes to carving out the exact online real estate you want to occupy, block lists just can’t do the job on their own. Advertisers can make their block lists more effective by using them in tandem with “white lists” of sites they do want traffic from. 

At the end of the day, however, they’re all just tools that require skilled use and diligence. Achieving precision and control in programmatic takes continual, proactive efforts to buy the right inventory and reach the right audiences.


Don’t Leave the Door Open to Unwanted Inventory

The chief problem with block lists is that they don’t actually do what advertisers tend to believe they do: that is, they are blunt instruments that can’t guarantee you’ll avoid unwanted inventory.

Advertisers are often drawn to block lists because they offer more scale by cutting out a small number of undesirable websites in the programmatic market and leaving plenty of available impressions to bid on.

But all that scale comes at the cost of control over your ad spend — no list of domains can possibly cover every unwanted placement on the programmatic market.

Even those sites that you’re expressly not interested in advertising on can slip through a block list. If they suspect they’re appearing on a lot of these lists, websites often change their domains or default content category. This is especially true for sites without established audiences, since few people will even notice the switch.

In other words, practically any site can fall off your list if you don’t regularly audit and update it.


Don’t Close the Door on Inventory You Actually Want

Similarly, block lists can also unintentionally prevent you from purchasing inventory that would actually serve your brand well.

For example, some ad tech services allow you to block entire categories of sites using keywords and contextual filters. And if you’re a marketer in agribusiness, for instance, you may be tempted to block all websites in the “food” category, since most are going to attract people interested in eating food, not growing it. You might also be tempted to block websites in categories that have nothing to do with your industry — like “sports.”

But think about all the publishers that post articles on these topics that you would be blocking in the process. TIME and The Huffington Post generate a lot of food- and sports-related content, but these publishers also both cover agriculture. And even if some content isn’t strictly about your industry, it still could easily grab the interest of people you want to reach — farmers check the internet for sports news, too!


There’s Always a Better Way

None of this is to say that block lists are useless and should be abandoned. It’s just that they’re a very simple tool being applied to a very complex problem. Programmatic ad exchanges are vast, and it’s impossible to vet everything you’re blocking — and even harder to vet everything you’re not.

Whether you decide to enlist these services or not, it’s worth recognizing that the real problem isn’t with block lists, but with any inherently simplistic approach to reaching audiences at internet-scale. Trying to buy all the right ad inventory is really just a game of “Whack-a-Mole” that block lists will never help you win. Instead of relying on these limited tools, advertisers should work with their programmatic media buyer to address brand safety and context.

The programmatic marketplace is always changing: new sites launch, old ones die off, and content categories and audiences evolve. Without constant attention and a wide range of other tactics, these tools simply can’t keep up.


  • Anonymous

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