First-party Email Data is the Future of Deliverability

Deliverability is an essential part of email success. After all, you can’t connect with your email audience if they’re not seeing your emails in their inbox.

What kind of email data are you mostly relying on to help you understand your email performance: first-party or third-party data?

If you’re using some of the most popular deliverability tools and techniques out there, you’re likely leaning heavily on using third-party data.

While most senders also incorporate some element of first-party data, if your focus on third-party data outweighs how much first-party data you use, your understanding of your email performance could be incorrect. This is why it’s critically important to understand the differences, benefits, and the limitations of both kinds of email data.

What is Third-party Email Data?

Third-party data is representative of an audience but is not YOUR audience. You don’t have a direct or real relationship with the data subjects and do not interact with them directly.

A good example of third-party data is a seed list. The seed list is a bunch of real mailboxes, and while they’re not mailboxes maintained by people who have freely given you their permission to email them, they’re not your real subscribers or customers. They are on the list owned by the vendor you’re using to get a better sense of how your mail might be delivered to your actual list of recipients.

Blocklists are another set of useful third-party data, and so are things like spam or sensor trap networks. Even Google Postmaster Tools (GPT) and Microsoft’s SNDS (Smart Network Data Services) are third-party data sources.

Third-party data can be useful for identifying broad trends, but it’s aggregated and anonymized, so it’s not as precise or actionable as first-party data. It should always be validated against first-party data for the most accurate insights.

Who Uses Third-party Email Data?


If you’re a marketer using one of the many popular email deliverability tools on the market today, you and those tools are both using third-party data! If you’ve ever benchmarked your performance against industry standards and competitors, guess what? Yuuuup. That trends report was fueled by third-party data.

Deliverability Vendors

In general, most deliverability tools use third-party data. For instance, if you buy an add-on tool to your email service provider (ESP) like Validity’s Everest, the data you’ll see in those dashboards are indicative of your performance based on seed testing results, blocklisting status, spam trap monitoring feeds, etc. But those are not numbers directly associated with your actual performance to the actual subscribers on your list. They’re aggregated estimates which should only be used as directional guidance.

Blocklist Operators

Blocklist operators also use third-party data. They set up addresses and collect data across multiple mailbox providers to detect abusive spammers via IP or domain. Remember, they aren’t just looking at their own mailbox to see if there is spam in it. They’re using data from across the email ecosystem to find those bad actors.

List Validation and Verification Vendors

List validation or verification services use third-party data to confirm if an email address is real. Similarly, spam trap feed operators use third-party data as well.

Overall, if you’re using deliverability tools to improve your email marketing instead of looking at delivery and engagement metrics within your ESP, you’re using third-party data.


That’s right! ESPs also use third-party data to inform decisions. Compliance teams make it their business to ensure their senders are not sending abusive mail, so they refer to things like blocklistings, bounce responses, feedback loop data from mailbox providers (MBPs), and more. We use this data to supplement what we know about our own senders’ performances as well.

Unfortunately, add-on deliverability tools and other services can be expensive, particularly when you’re sending at scale. So, when you add that to the fact that the info is directional in nature, and not reporting on your actual email performance to actual subscribers on your list, it isn’t unusual to wonder why anyone chooses to use third-party data: if it’s not real engagement information from my real list subscribers, what’s the point? What can I learn from it?

Well, despite its limitations, third-party data is still widely used within email marketing today.

Let’s unpack that.

How Can You Use Third-party Email Data?

Third-party data can be used to gain broader market insights, highlight problematic trends in performance, show you if you how things might look in an inbox, and even tell you if the email has a good chance of reaching a mailbox at all.

There are a bunch of different ways to use third-party data to give you those broad understandings:


Email rendering tools use third-party email data and can be a great option for testing your email creative across a variety of devices, email clients, and MBPs.

We also mentioned seed lists earlier because they’re a great example of third-party email data at work. Sending mail to a seed list can give you a general sense of how an email campaign might be received. Do the addresses on the list bounce the mail because it failed authentication? It’s great to know that via a test list before you send mail to your real folks – you can fix your authentication before you kick off the campaign.


Lots of senders decide to use seed lists to monitor their performance, too, by seeding all campaigns and watching trends over time. Keep in mind, these are not necessarily a direct indication of actual user engagement.

MBPs can very easily tell the difference in behavior between a seed address and a mailbox managed by a human, so if you see something amiss in your test results (e.g. inboxing percentage drops from 90% to 30% at Gmail), go check your actual sending statistics. Do you see a higher-than-normal bounce rate or a drop in open rate at Gmail? If not, you’ve likely just uncovered a(nother) false positive…they’re very common with seed testing.

You can also use dedicated deliverability tools to watch email performance, like using a platform where it tracks spam trap hits on a trendline.

Another way to use third-party data to monitor your email performance is by referencing data feeds from Spamhaus or similar blocklist operators. That’s using third-party data!

Assessing List Health

If you’re using a single opt-in method where people can provide their email address and go on their merry way without confirming it’s valid, even homegrown lists can be riddled with bad addresses. Using a list validation service (third-party!) can help you assess the quality of the list without the damage that would come from learning it the hard way (also known as mailing and hoping for the best).

The problem with third-party data is that you can’t rely on it for detailed, specific insights into your audience’s behavior. It’s directional, historical, and uses approximations to report on what may happen with your real send. It doesn’t incorporate your actual sending statistics or use any kind of predictive technology to help you know what will happen…Instead, it asks you to look at past patterns and make an educated (and hopeful) guess about it happening again in the future.

It’s almost 2025, though. Shouldn’t we be able to do better?

What is First-party Email Data?

When it comes to email, first-party data is your real audience. All the information you’ve collected directly from your list full of real customers with addresses provided by the individuals who own them is first-party data.

Since this information is tied to your brand and the engagement of the real recipients on your lists, this data isn’t just directional like third-party data. This is specific, relevant, accurate insight tied to all the contextual nuance of your email program, allowing you to have a deeper understanding of your customers’ journey and lifecycle.

First-party email data is also related to your sending IP and domains. So, if you’re listed on Spamhaus or a similar blocklist, this knowledge is first-party because your real IP is facing a real consequence that you can see within the data.

Simply put, first-party data is real data about you and your activity.

Who Uses First-party Email Data?

In some ways, we are all using first-party email data. So long as you’re sending email via an ESP and that ESP can tell you how many emails you’ve delivered, you have access to first-party data. How you – and they – use first-party data varies broadly, with advanced usage typically requiring better integration and analytics capabilities.

Let’s look at some common use cases:

Email Service Providers

ESPs can give you first-party email data because they are seeing and facilitating your email programs. Depending on their capabilities, you can get real information amount things like delivery and bounce rates, opens, clicks, and other engagement signals.

An important note here, though: Most ESPs have basic reporting capabilities, which is why those deliverability tools with third-party data can be appealing. While your ESP might tell you 900 of your 1000 processed emails were delivered, they rarely tell you why those 100 undelivered emails weren’t successful.


If you do something as simple as honoring an unsubscribe request or segmenting recipients based on activity, you’re using your first-party data. Marketers have lots of ways they can (and should) use first-party email data, especially if they have access to robust data sets. We’ll look more closely at what they can do with certain data in our next section.

So…Why Do People Use Third-party Data if First-party Data Exists?

This isn’t a simple answer, so let’s pick it apart a bit.

If you’re watching the trends, third-party data does give you a sense of how you’re doing. For instance, if you send to a seed list with lots of Gmail addresses on it and all of the mail is going to spam when it usually lands in the inbox, you know you might have the same disastrous results with the Gmail folks on your real lists! That’s a helpful tidbit of knowledge and a compelling reason to use a seed list.

Additionally, but unfortunately, making use of first-party data can be expensive! Let’s say you’re an enterprise brand wanting greater insight from your first-party data. First, you’ll need to get an engineer to build a system to process your data and we know good tech talent isn’t cheap. Then to analyze the data for insight, you’ll need a trained data analyst and/or a business intelligence tool. Both of those options cost a pretty penny as well, and unless the tool or the specialist is also highly knowledgeable about email, those insights don’t come with useful context. We regularly hear stories from our fellow practitioners about how the data they’re relying on to drive their decisions isn’t even accurate, despite all the time and money spent processing it.

Taking all of this into consideration, you’re likely starting to see why third-party data has been so widely adopted within email marketing. First-party data simply hasn’t been accessible enough for most senders to make good use of it. But in an ideal world, third-party data should be used as a supplement to first-party data, not a leading indicator for decision making.

It would make a lot of sense for an email-specific company with access to both third- and first-party data to create the tools and analysis required to harness more power from that first-party data…But remember, we said ESPs generally don’t have a ton of analysis connected to first-party data.

Well, until now, at least.

How SocketLabs Spotlight Uses First-party Email Data

We decided to tap into that well of data and do something meaningful with the information. Now, our customers can see and use actual, real insights into their performance using data from their true performance.

Before, your surface-level first-party data lived in your ESP while your deliverability and performance insights were siloed in a third-party data-enabled platform elsewhere. This leaves you on the hook for cobbling together insights from disparate sources and tools.

That’s no longer your only option.

Now, when you look at your SocketLabs Spotlight dashboards, you’re seeing a combination of first- and third-party data with advanced analytics layered right on top. We not only report the information available at most ESPs, but we also provide an additional layer of analytics, thanks to the logic we’ve built on top of our data processing capabilities.

Check it out:

SocketLabs Spotlight email analytics users get:

  • Recipient-level information: You can directly tie performance to recipient. You can determine who received your mail, then how they interacted with it, to help you put together more intelligent, engagement-based segments for better targeting.
  • Reputation scoring: Your StreamScore, a numerical assessment of your sender reputation, is based on both positive and negative engagement you’ve actually received in combination with the same kinds of third-party signals you’d get from an external deliverability tool.
  • Contextual or/and actionable data: Since we process and deliver your real mail, we know when your mail is bounced. Unlike other ESPs, we can connect the different data-dots to show you why it failed and give you recommendations for fixing the source problem. These Guided Insights build a contextual bridge between something like a high hard bounce rate and a poor-quality distribution list: Maybe you have a data collection problem!

Since we just got done telling you how this level of processing on first-party data is prohibitively expensive, you might be wondering how this is even possible, let alone accessible for users of an affordable platform like SocketLabs.

We have a not-so-secret weapon…

We’re Powered by Snowflake

This is all possible because we are Powered by Snowflake. We built all our analytics on top of Snowflake’s ability to process millions of data points in seconds. We let them do what they do best (processing data) while we apply what we do best (apply our email knowledge) to create a deeply informative and contextual analysis of your actual email performance.

Plus, not only can you get more from your real performance data, you can get more of it – to the tune of up to 13 months of your real data in comparison to competitors’ ability to give you 30 days.

What You Can Do by Combining First- and Third-party Email Data

True insight from first-party data, especially when combined with trusted and familiar third-party data, can significantly change your email performance because you’re able to more confidently connect a cause and effect.

If we notice a high percentage of unengaged users at a particular mailbox, we not only tell you that, but suggest corrective actions to link your problem directly to a solution.

Even if you send mail via multiple subaccounts or streams, you can get pinpointed insight into each performance to help you understand where you need to focus your efforts.

Using SocketLabs Spotlight email analytics truly gives you a three-dimensional look at your performance. Not only are you getting directional information like you would from a traditional third-party data tool, but you’re also getting advanced analysis of your true performance…based on the actual humans you’re sending to, not seed addresses.

We’re also working on some really cool predictive features we’ll be announcing very soon, but that’s all we can say about that for now…

Insightful First-party Data is Finally Accessible

At the very end of the day, third-party data isn’t your actual performance. It’s “similar” to your performance. Why choose an email solution that gives you only one half of the data available to you, requiring you to get advanced insights (that are still not REAL insights!) elsewhere for more money?

Now that SocketLabs gives you the ability to have the same kind of visualizations, analysis, and insights you used to only get from third-party data on your actual first-party email data, there’s really no reason to rely on data that’s not yours. Let’s talk about the future of your email performance.

Table of Contents