Ad buyers are dissatisfied with publishers’ slower-than-expected adoption of the industry’s anti-fraud initiative, Ads.txt. Now they are nearing an ultimatum: Publishers need to upload a public list of their programmatic sellers and resellers, or they will be left out of brands’ programmatic ad buys.

“Some advertisers care a lot about making sure that we’re not buying fraudulent inventory, and for those I think it will be as soon as Q4 that we start to say, ‘We’re only buying through Ads.txt-enabled publishers.’ Something like that is going to need to happen sooner than later to actually push the publishers to where they need to be,” said DigitasLBi’s VP and director of programmatic, Liane Nadeau.

Resolution Media, which oversees technology-based media buying across Omnicom Media Group, has created a program called the Inventory Authentication Initiative to reduce the amount of fraud sold to its clients. Enforcing Ads.txt adoption is a pillar of that program.

“We’re mandating our publisher partners adopt Ads.txt for all of our open exchange buying. So we’re requiring any and all publishers that we partner with on a programmatic basis to implement the protocol with an aggressive but what we feel is achievable timeline,” said Resolution Media president George Manas.

Manas declined to specify the agency’s exact timeline for enforcement, but he did wink at one. Execs at Forbes and Google told me last month that advertisers and the DSPs (demand-side platforms) they use to buy ads programmatically plan to start enforcing Ads.txt adoption in the fourth quarter of 2017. Asked how that timeline aligns with Resolution Media’s, Manas said, “What we’re always looking for is to beat the market for our clients. So I would emphasize the ‘aggressive’ part of ‘aggressive and achievable.’”

Why Ads.txt is an urgent issue for advertisers

The buy side is aggressively adopting Ads.txt for good reason. By only buying inventory available from the listed supply-side platforms (SSPs), advertisers can mitigate the amount of fraudulent inventory in the market.

One of the biggest sources of ad fraud is called domain spoofing, which can be used to avert the whitelists and blacklists that advertisers institute to specify which sites can and cannot feature their ads.

Here’s how that works: A site like can sell ads through an open ad exchange alongside inventory from more reputable sites. But no reputable advertiser wants to buy ads from, especially if they’re using whitelists and blacklists. So when has an ad slot to sell through the exchange, it changes the domain name on the bid request to, and advertisers looking to buy ads on The New York Times’s site end up purchasing ads from “It’s something that isn’t able to be stopped before bids are made,” said Nadeau.

Ads.txt enables advertisers to avert the issue. Instead of taking the domain name on a bid request at face value, the advertiser, through its DSP, can cross-reference The New York Times’s Ads.txt file. First, it can see if the Times sells ads through the particular exchange that is using. And if it is, then it can check that the unique publisher ID attached to the bid request matches the one listed on the Times’s Ads.txt file. If it doesn’t match, then the DSP knows that the inventory is fraudulent and can opt not to buy it.

Publishers’ level of adoption is ‘disappointing’

However, the success of Ads.txt in fighting ad fraud depends on both sides of a programmatic ad sale participating. Advertisers and agencies are prepared to base their programmatic ad buys on publishers’ Ads.txt files. And DSPs like MediaMath have already built tools to check a publisher’s Ads.txt file when placing those buys on a brand’s behalf. Now they are waiting for publishers to meet them halfway.

“We are ready for it. Our DSPs are ready to implement this. And we’re really just waiting on the inventory,” said Nadeau.

The wait has surprised executives on the buy side. “The original estimation was adoption was going to pick up speed and peak over the summer. And that hasn’t really happened,” Lewis Rothkopf, general manager of supply at MediaMath.

While the IAB Tech Lab only released the finalized Ads.txt specification in June 2017, it doesn’t take long for publishers to implement it. Dotdash was able to wrangle a list of its programmatic sales partners across six sites in a day. And while Forbes needed up to two weeks to compile and check its list, programmatic sellers like Google and Amazon have actively assisted publishers to speed up the adoption process. And yet “publisher adoption has been super disappointing,” Rothkopf said.

“We’re still seeing some slowness in terms of publisher adoption, which is going to be an issue. It’s something that, as we look towards next year, it’s going to become essential for us,” said Rich Sobel, senior VP of solutions and partnerships at Publicis Media.

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