Merkle on Tuesday launched Merkury, an identifier designed to allow marketers to continue targeting audiences online without using third-party cookies.

Merkury uses technology from Merkle’s recent acquisition of 4Cite, a first-party publisher tag that lets media owners retarget audiences over email and on platforms such as Facebook by matching hashed email addresses.

Here’s how it works: Publishers embed the 4Cite tag, renamed the Merkury tag, onto their sites, which embeds Merkle’s first-party cookie into the publisher’s first-party domain.

If enough publishers incorporate the Merkury tag, it’ll create a vast network of first-party cookies overseen by Merkle. Buyers can combine their first-party data with Merkle’s proprietary data, which includes PII-based identifiers such as hashed email addresses, to build and find audiences across the Merkury publisher network. By matching hashed email addresses to the Merkury tag, advertisers can target audiences on those sites.

Because publishers are embedding the Merkury ID into their first-party domains, buyers don’t have to match audiences across publishers, Lee said. Rather, they’re matching audiences across the Merkury network against Merkle’s owned PII-based data set, for which the main identifier is hashed email addresses.

“Email is the key identifier,” said John Lee, chief product and data officer at Merkle and global president of Merkury. “It allows brands to be compliant while still being able to connect that email address to first-party cookies.”

Merkury launches with integrations into the SSP Index Exchange and the DSP MediaMath, Merkle’s tech partners for audience targeting platform M1.

So far, the publisher network includes a dozen “significant publishers,” including Pandora and Meredith, Lee said. And Cadillac is using the solution along with a handful of other Merkle clients.

Not cookieless – yet

Merkury technically works, but industry adoption and evolving privacy regulation will determine whether the solution is able to scale and remain viable long term.

Both M1 and Merkury will rely on third-party cookies until Google Chrome phases them out over the next two years, to ensure their audiences scale. During that time, Merkle will slowly migrate buyers toward cookieless matches. While Merkle’s Publisher Addressable Marketplace (PAM) currently uses cookieless integrations for roughly half of the matches it makes with publishers, it’s still using cookies “as the last mile,” Lee said.

Merkle is trying to get more publishers to use its tag by offering free implementation, but it’ll need to be scalable when third-party cookies are finally deprecated by Chrome.

“We’ve got two years, and people can’t flip a switch overnight,” Lee said. “It will enable people to prioritize first-party addressability, but let them spill over into third-party while it’s available.”

Another question is whether Chrome will consider Merkury a “workaround” that violates the ethos of consumer privacy protections and crack down on the methodology, just as it cracked down on tactics like fingerprinting.

But because Merkury leverages first-party relationships and gives consumers the appropriate opt-out mechanisms under CCPA, it’s in the spirit of what these companies are trying to accomplish, Lee said.

“We think all of this puts us in alignment and not at odds with what regulators and browsers are trying to do,” Lee said. “We don’t believe, nor have [Apple or Google] stated, that their goal is to end targeted advertising. That being said, we will all have to wait to see how this develops.”

The business of Merkury

The Merkury ID is integrated with M1, Merkle’s PII-based data platform used by Dentsu agencies to discover and target audiences. Merkle plans to integrate the Merkury ID with CDPs from major marketing clouds so it can be used across paid, owned and earned channels.

The Merkury tag will be immediately available to publishers that participate in PAM, which facilitates server-to-server integrations with Pandora, AOL, Time Inc., Weather and others.

“We’re going to remove the third-party cookie as the currency and we’re going to replace it with the Merkury ID,” Lee said.

Merkle plans to sell the Merkury ID across the market regardless of relationships with parent company Dentsu, positioning Merkury against independent ID solutions from LiveRamp and Neustar.

Companies licensing the Merkury ID can bundle in services from Merkle’s consulting, systems integrations and analytics services on an FTE to help deploy the technology. Currently 300 Merkle staffers are working on the Merkury product.