Acceptable Ads whitelisting infrastructure explainer

What’s with whitelisting ads in an ad blocker? What is it even? Can’t count the times you sat up, maybe with a pipe, definitely with a monocle, and surely with your favorite night-time beverage, ruminating on these mysteries?  Are you doing it right now?


Well, now you might be – But the point is that people have asked us these questions countless times. Many users familiar with what we do at Acceptable Ads sometimes think whitelisting is when an ad meets the Acceptable Ads standard. True, that’s the first and most crucial step for an ad to be whitelisted. But it actually refers to something different: it’s the process of getting that compliant ad shown to the almost 200 million users who have downloaded ad-blocking software and have the Acceptable Ads feature enabled.

Whitelisting is a catch-all term that sounds simple, but refers to the complex infrastructure that eyeo has built up over the years to serve the digital advertising supply chain. Some people know about it, but often it’s at best ‘sort of’ understood. This blog will focus on giving a better understanding of how this infrastructure was built, how it works, and where it’s going.


*(If you’re looking for how the Acceptable Ads Committee works, see this explainer; if you’re looking for a glossary of terms, like “whitelist,” that I’ll use below, see this exemplary copy and/or if you’re wondering how the criteria for the Acceptable Ads standard are made, see this piece.)


How’d you build that?


It all started with Acceptable Ads – the idea that ad blocking in its no-holds barred, block ‘em all original form was too extreme and that the value exchange between ad-blocking users and publishers could indeed be re-established by ‘filtering’, ie. not blocking all ads. Though, ultimately that’s just theory: I mean, how do you actually show millions of users nonintrusive, respectful formats? How’s the sausage made, that is? That’s whitelisting. 


It all seems pretty basic when you consider how ad blocking works in the first place. An ad blocker only blocks what it’s told to. It’s told what to block by a block list of URLs. These block lists can earmark almost any web element to snuff out of your surfing: ads, trackers, cat pics, whatever. Here’s a website of the most famous (independent) group that makes EasyList. There you can view an actual block list, which looks like this:



Whitelisting works by making an exception list, which unblocks elements by countermanding the block list. It looks very similar to a block list. Here it is, and here’s the technical way to write blocking or unblocking filters.


Starting the process


When someone from the digital ads supply chain decides they would like to whitelist ads, they contact eyeo. A representative at eyeo then works with that person to investigate whether their ads fit the criteria established by the independent Acceptable Ads Committee. Sometimes the ads already fit; when they don’t, it’s often possible to adjust the ads – by changing position, removing animation, tightening up labeling, etc. – so that they can be whitelisted. In some instances, like a pop-up or a long, auto-playing video ad, no adjustment can make it acceptable and that particular ad is rejected. 

Once the ads fit the criteria, they are added to the whitelist and participating ad blockers (Adblock Plus, AdBlock, Crystal, etc.) and mobile browsers that come pre-baked with ad-filtering software automatically show that ad to all users (unless that user has decided to turn off Acceptable Ads and “block ‘em all” – which they can of course always do).


Managing partners and monitoring


When someone is interested in whitelisting, there are dozens of people within the company who make sure that someone – whether a publisher, ad network, or advertiser – gets what they need. The main two pillars of that process are managing partners and monitoring for acceptability.

To make this all a bit more tangible, I decided to interview two eyeo employees integral to whitelisting, one who works in partner relationships and one who works in monitoring. After all, I can tell you how it looks from the outside, but if you want to know how the sausage is really made, you gotta talk to the butcher.

Caroline Louwette has been working in business development at eyeo for over five years.



Berit Graf started working part-time for eyeo as a student about two and a half years ago. She is now the Section Lead for Acceptable Ads Monitoring.



The process of whitelisting starts with Caroline. Sometimes, she and other account managers find new partners and sometimes those partners find us. Once there’s a connection, Caroline works with the potential partner to see if their ads fit the Acceptable Ads standard. “We historically come from the supply side [publishers],” she said. “In order to cater to [ad blockers], there normally needs to be a client-side detection.” The client here would be the publisher who, after getting their ads in line with the Acceptable Ads standard, would apply an “if/then rule” to their website that would separate the ad blockers from the non-ad blockers. The rule works like this: If there is a whitelisting user, then I will serve them an acceptable ad but the rest of the readers get the ad that would normally run there. 


But how do we know they won’t start breaking the rules? What’s stopping them from, say, running video ads (not acceptable) in a spot where an acceptable ad is supposed to run? It’s not a what that’s stopping them, it’s a who: Berit and her team protect whitelisting users from ads they might not like. “I’m fine being the police, that’s alright,” Berit told me, with a laugh. 


Maybe you thought there’s a magical bot crawling the internet looking for violations? Of course, there is a bit of truth to that, as they are constantly improving the process, including trying to automate where possible, but manual work will always be needed. “The problem is,” she continued“… even if we were to automate the whole process, in the end it always needs manual work to check [the] issues.” There’s also timeliness: issues found by the monitoring team get moldy on the shelf: “If we sent them 1000 test case issues that we found, there would be a huge delay in post-processing them,” she explained. Then they would neither be current nor reproducible. 


How do Berit and Caroline work together?


Whereas eyeo used to handle everyone interested in whitelisting directly, as Acceptable Ads has expanded, independent solution providers have stepped in to broaden and enrich the possibilities. eyeo still handles the task of whitelisting and monitoring, but whereas Caroline’s job may have previously focused on new clients, it has shifted to include a lot of account management as well as consulting. She works with a group of technical account managers, so that each partner gets a consultant (a Caroline, that is) and one technical account manager. When a new partner comes in, Caroline’s team and Berit’s team collaborate on adding them to our list. 


But what happens when a violation occurs? That is, what happens when the police have to lay the smackdown? 


First off, it’s important to know that the monitoring team is primarily checking to make sure acceptable ads are shown, not looking for infractions. This is work that starts in Berit’s neck of the woods, but then includes Caroline’s group and the technical account managers. The main task is making sure partners’ acceptable ads are working and providing metrics to those partners, a typical client-agent relationship in ad tech.


If a violation is found, however, it first must be verified by yet another eyeo team: the filter list managers. After these engineers have a look, it goes to the responsible technical account manager for a second verification before it is communicated to the partner. And usually it’s nothing sexy: just a technical issue that’s fixed in an hour or so.


But what about the worst violation they ever dealt with? 


Berit mentioned some of the funny ads her team of web-scouring, meticulous souls had uncovered, but at no time were people blatantly flaunting the rules. There are of course guidelines: through the work of Berit, Caroline and others, there are several internal documents to help the various teams check and comply with the criteria. But ultimately, monitoring for any kind of compliance in the often unpredictable world of programmatic advertising carries a sour aftertaste. Despite the fact that it’s done for the best of intentions – to ensure brand safety, protect quality or, in this case, to protect users – it is painstaking, experimental, and sets up “difficult conversations.”


“Monitoring is necessary but totally underappreciated,” Caroline told me. “Because it’s … unpleasant communication [with valued partners] – you’re talking about problems, not about growth and something nice that both parties like.” 


It’s a must though. Acceptable Ads would implode without some “policing.” Users would storm the exits, rightfully decrying ad-filtering software that had lost its way and choosing a scorched-earth ad-blocker setting that doesn’t allow the option to filter. It’d never come to that though – eyeo and the AAC wouldn’t allow it.  It’s a “long process, involving many people and teams,” Berit noted; but we’ve got your back.

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