MediaMath, one of marketers’ more widely-used platforms to buy digital ads, announced Thursday that it will begin aggressively rolling out the “ads.txt” intiative across its entire supply footprint.

As such, another major player in digital advertising has joined the industry’s latest bid to cripple ad fraud. And yet, hurdles remain.

If it’s hard to get excited about something called ads.txt, understand that it’s very much one of the hottest and most important topics in marketing right now.

It was introduced earlier this year to stop the monstrous problem that is domain spoofing. Ads.txt is basically a publisher-issued seal of approval that says someone offering ad inventory from the Washington Post really does represent the Washington Post.

Domain spoofing is what happens when criminals offer ads on but through digital sleight of hand actually serve them to, say, In that scenario, the Washington Post loses revenue and marketers waste money buying ads that nobody sees—unless you count the programs built by fraudsters to simulate human web traffic.

By all accounts, domain spoofing is the largest threat to the digital ad economy.

The Financial Times recently came out and said at least $1 million of phony ad inventory had been sold under its name for an entire month. In another case, marketers were bilked out of $3 million to $5 million a day for more than a month by Methbot, widely regarded as the largest domain spoofing scheme to date. Even high-level insiders at top-tier fraud detection companies say they’re having an extremely difficult time stopping sophisticated scammers who deploy cutting-edge domain spoofing tactics.

To stop the bleeding, the Interactive Advertising Bureau’s Tech Lab created ads.txt, a simple solution that makes it significantly harder for scammers to spoof domains. Procter & GambleGoogle and many other large players in the industry have already put their weight behind it. MediaMath’s move gives it even more momentum.

Waiting game
Still, the company stopped short of saying it would implement the measure immediately. And for good reason: Publishers aren’t adopting ads.txt fast enough. That’s a big problem, because marketers want to reach as many people as possible. However much they hate ad fraud, they’re not going to use ads.txt if it means restricting their online advertising to a relatively small pool of publishers.

Only 12.8 percent of the top 10,000 websites have adopted ads.txt so far, according to Ben Kneen at Ad Ops Insider.

And some of the websites that have adopted ads.txt are called Daily Natural Remedies, Daily Health Remedies or Celebrity Life Journal…. You get the idea: Ads.txt does not equal premium content.

MediaMath waited until now to make its announcement because it was “very concerned about the slow rate of adoption,” says Lewis Rothkopf, general manager of supply at the company. But he’s optimistic that enough publishers will sign on within 9 to 12 months.

“There’s a balance we have to find, so we can’t fully go to adopting ads.txt right away,” Rothkopf says. “We need to be sure we give publishers an opportunity to be compliant, but at the same time, we are definitely not open to exposing our customers to risk of fraud.”

MediaMath already sells from what it calls its “Curated Market,” which comprises premium publishers with a strong track record of delivering ads to real humans and not bots. Rothkopf says the company detects fraud on less than 1 percent of the consumer impressions sold there.

For now, advertisers can still use MediaMath to buy from publishers that don’t use ads.txt if they so choose. But the buyers and sellers outside ads.txt seem likely to keep shrinking. After Google recently fell victim to a never-before-seen type of ad fraud, the company said it will soon only buy from publishers that have adopted ads.txt.

“I think we’re overall moving toward a flight of quality and brand safety,” Rothkopf says. P&G Chief Brand Officer Marc Pritchard and Google “did the entire industry quite a service by putting their entire weight on this.”

Large agencies such as Digitas have also come out and said they will only buy from publishers on the ads.txt train. As U.S. publishers’ participation picks up steam, as many expect, the scale problems holding it back right now should ease.

Then marketers can confront the next problem: Ads.txt is not likely to spread so easily in the rest of the world.

Read on AdAge.