Validity launches Heatwave to combat synthetic domain warming

Validity, the leading provider of Enterprise AI solutions for digital marketers, has introduced Heatwave, a new email blocklist designed to combat unethical cold email practices, particularly synthetic domain warming. This innovative tool leverages millions of targeted data signals to help mailbox providers and email service providers (ESPs) identify and mitigate the use of manufactured send reputation through artificial engagement.

Heatwave draws on an extensive analysis of data points from Validity’s Intelligence Network, which has already flagged over 1 million domains exhibiting unethical email warming behaviors. Users can query the Heatwave list via lookup.validity.tools to gain insights into potentially deceptive practices.

Deceptive domain warming services often connect to a customer's email tenant, creating domains that mimic the customer's own and generating synthetic messages, opens, clicks, and replies between networks of fake accounts. This practice feeds false engagement signals into systems used by mailbox providers like Gmail and Outlook to determine the legitimacy of a sender.

Tom Bartel, Senior Vice President of Data at Validity and board chair of M3AAWG, explained, "Email works because people trust it, and that trust depends on the integrity of the signals behind the inbox. When reputation is manufactured instead of earned, it's just plain cheating, and the whole ecosystem suffers. Heatwave gives the ecosystem another signal to identify unethical gaming behavior and act on it."

The Heatwave signal is now integrated into Validity’s existing domain name system (DNS) reputation zones, providing additional context to mailbox providers and ESPs. This integration ensures that partners like Comcast, Proofpoint, Spamhaus, and SURBL have access to the Heatwave signal without needing to consume it separately.

For ESPs, Heatwave identifies customers who have built their sending domain reputation on artificial warming rather than legitimate list development. For mailbox providers, it acts as an additional filtering tool for domains whose reputation was synthetically constructed. The list is growing, with existing global partners from the email ecosystem already evaluating or using the Heatwave signal.

Alex Brotman, Senior Engineer at Comcast, commented, "This particular signal is interesting because reputation relies on senders intentionally behaving ethically and doing the right thing. Nobody likes shortcuts, and nobody likes deception."

Carel Bitter, CEO at Spamhaus, added, "Attempts to manipulate email reputation are not new. Our work with Validity on Heatwave gives us an additional signal we can use to correlate domains and better understand the infrastructure behind this activity. That added context helps us identify patterns earlier and respond more precisely."

Mariska Calabrese, VP of Security at beehiiv, stated, "Synthetic domain warming is a direct violation of beehiiv's Acceptable Use Policy. Manufacturing fake engagement to trick an inbox into trusting a sender isn't legitimate; it's deception. Signals like Heatwave help us and the rest of the ecosystem hold that line, protecting the senders who play it straight from being crowded out by the ones who don't."

Heatwave is part of Validity’s ongoing work with organizations across the email ecosystem to address practices that undermine trust in email. Validity participates in industry standards bodies and anti-abuse initiatives, including M3AAWG, ETIS, Signal Spam, ESPC, and BIMI. The company works closely with mailbox providers, ESPs, and other industry partners to address email reputation and deliverability.

Mark Briggs, Founder and CEO of Validity, said, "For more than 25 years, Validity has been committed to being a force for good in email. We have visibility into the email ecosystem that nobody else has, built on a data network we've spent decades developing, and partnerships across the industry that put that visibility to work. Heatwave is that commitment in action, using both to make email safer and more trusted for everyone."

Validity has been at the center of the email ecosystem for nearly 30 years, shaping standards and earning the trust of the world's biggest brands and mailbox providers. The company’s data-driven foundation powers its Enterprise AI email platform, Validity Engage, helping enterprise teams know what to send, when to send it, and who's ready to receive it.