Hashed Emails: Why They Matter for Publishers

Before we talk about email hashing, we first need to discuss the context – the history of third-party cookies. Cookies were originally invented to help websites track their visitors and what sites their visitors previously visited. They essentially function as a tracking code placed on a user’s device, allowing sites to recognize returning visitors and tailor content accordingly.

Ever search for something like Rayban sunglasses, and have Rayban ads follow you across the internet? Those are cookies in action.

For years, digital advertising relied on third-party cookies to deliver highly targeted ads. But as browsers like Safari and Firefox started blocking them, and Google Chrome began phasing them out in 2021, the industry faced a major shift. The issue? Third-party cookies allowed advertisers to collect user data and track browsing behavior with little oversight.

Enter privacy laws like GDPR. Under these regulations, websites must obtain user consent before storing third-party cookie data. This means giving visitors control over their data, whether that’s opting out completely or selecting which cookies they allow. Even with these measures, users still continue to demand more transparency and control, pushing the industry toward cookie-free solutions.

Now, while Google has temporarily hit pause on its plan to deprecate cookies, the movement toward privacy-first advertising is going full steam ahead.

As a publisher, adopting cookie-free solutions is important for maintaining audience targeting, personalization, and revenue streams while staying compliant with privacy regulations. There are several third-party cookie alternatives out there, but today we’re looking at email hashing.

Let’s explore how it works and why it matters for your business.

What Is Email Hashing and How Does It Work?

Email hashing transforms a user’s email address into a unique, irreversible string of characters, known as a hash, using cryptographic hash functions like SHA-256, MD5, or SHA-1.

Here’s a simple example:

• Original email: [email protected]
• Hashed output (SHA-256): 9b74c9897bac770ffc029102a200c5de.d5d3dcd3c8a12315f28d56d7a1e73a

Since hashing is deterministic, the same email will always produce the same hashed value. This allows for consistent cross-platform recognition, without exposing personally identifiable information (PII).

Put simply, hashed emails let you recognize users across different devices and platforms while using encryption to keep their data secure and private.

Why Should Publishers Use Hashed Email Technology?

As a publisher, you’re likely trying to balance multiple priorities: user privacy, ad revenue, audience targeting, and compliance. Email hashing helps you achieve all of these, and the great thing is pretty much everyone has an email address. Here are the benefits of hashed emails:

1. Privacy Compliance Without Compromising Personalization

Privacy laws like GDPR and CCPA require responsible data handling. Because hashed emails anonymize user data, they allow you to recognize returning visitors without storing their actual email addresses.

2. Cross-Platform Identification

Cookies are tied to specific browsers and devices, which means if a user switches from their phone to their laptop, their identity is lost. Hashed emails solve this problem.

For example, if a user logs into your website from their phone and later on their desktop, you can still recognize them through their hashed email, ensuring a seamless and personalized experience across devices.

3. Stronger Audience Targeting

One of the biggest challenges in a cookieless world is maintaining effective audience targeting. But with hashed emails, you can continue segmenting users based on their behavior and preferences.

For instance, if a user subscribes to your newsletter and regularly reads articles about fitness, you can still serve them relevant fitness-related content and ads without using cookies. Because hashed emails result in more targeted, and therefore more effective campaigns, advertisers are willing to pay more, boosting your CPM rates.

4. Better Data Security

Raw email addresses are high-value targets for cybercriminals. Hashed emails significantly reduce this risk because they are encrypted and irreversible. Even if a hashed email database is leaked, it’s practically useless to attackers, as the original email addresses cannot be easily reconstructed.

How to Collect Email Addresses

To make email hashing work, you first need a strong first-party data foundation, and that starts with collecting email addresses directly from your users. Here are a few ways to do that:

• Newsletter Sign-Ups: Offer valuable content like weekly digests, breaking news alerts, or curated insights in exchange for an email address. Make the benefits clear and keep the sign-up process simple. Just a name and email field often does the trick.
• Loyalty or Membership Programs: Give users a reason to engage beyond content. Exclusive perks, early access to features, or rewards for engagement can incentivize users to create an account or subscribe with their email.
• Gated Content: Place high-value content, like eBooks, whitepapers, in-depth guides, or premium articles, behind an email gate. This is especially effective if the content solves a specific problem or provides unique insights.

Once collected, these email addresses can then be securely hashed and used for targeting, personalization, and monetization. For a more in-depth guide on how to create a first-party data strategy, check out this blog.

Challenges to Consider

While email hashing is a great alternative to cookies, it does have some limitations:

• Standardization Can Be Tricky: Not all platforms use the same hashing algorithm, which can lead to mismatches. To avoid compatibility issues, stick with widely accepted options like SHA-256.
• People Change Emails: If a user updates their email address, the original hash becomes outdated. That means the link between sessions can be lost. If you’re managing user accounts, it’s worth encouraging users to keep their email addresses up to date.
• It’s Still Personal Data: While hashing does help with privacy and adds a layer of anonymity, it’s not a free pass. Hashed emails are often still considered personal data under laws like GDPR and CCPA. Make sure your setup stays compliant as privacy regulations evolve.

The Bottom Line

Email hashing offers a secure, scalable way to balance user privacy with effective audience targeting, but it’s just one piece of the puzzle.

For a well-rounded, privacy-first strategy you should experiment with:

• First-party data collection: Encourage users to sign up for newsletters, loyalty programs, or gated content. By collecting email addresses directly, you build a valuable database of engaged users who have willingly shared their information.
• Contextual targeting: Serve ads based on the content users are actively engaging with rather than tracking their browsing history. For example, an article about hiking gear is a natural place to show ads for outdoor equipment brands, without relying on cookies or behavioral tracking.
• Alternative ID solutions: Besides hashed emails, there are other ways to build user profiles while respecting privacy. These other ID solutions provide advertisers with a cookieless way to reach audiences in a privacy-compliant manner.

Want to discuss how email hashing and other cookieless alternatives can benefit your business? Get in touch with one of our AdOps experts at Snigel today!