Is Substack Tracking Your Email Opens?

Every Substack newsletter you open sends a signal back to Substack's servers before you read the first word. That signal records when you opened it, on which device, and through which email client. Tens of millions of readers assume they're just reading independent journalism — they're also participating in a substack email tracking system that rivals what dedicated email marketing platforms do. Here's exactly what's happening, what writers can see, and how to stop it.

Key Takeaways

• Substack embeds a 1x1 tracking pixel in every newsletter email, delivered through Mailgun's infrastructure, which fires when you open the message.
• Writers can see a per subscriber activity rating, open history, and click data through their Substack dashboard — not just aggregate statistics.
• Substack routes email through Mailgun and embeds more tracking data in its links than Mailgun itself does by default, according to an independent technical analysis.
• Gmail's image proxy partially masks your IP address and device from the tracking pixel, but the open event itself is still recorded.
• Blocking the tracking pixel requires a dedicated browser extension — native Gmail image settings block all images, breaking newsletter readability.

Does Substack Track Email Opens?

Yes — Substack tracks email opens using a standard tracking pixel embedded in every newsletter it delivers. Substack's own support documentation confirms the mechanism: a tiny image loads from Substack's servers when you open the email, and that load event is recorded as an open.

The platform uses Mailgun for email delivery. Mailgun's infrastructure handles the actual send, but Substack layers its own tracking on top. A technical investigation found that Substack embeds significantly more data inside its tracking links than Mailgun does by default — meaning the data collection goes beyond what the delivery provider requires.

Substack also counts opens by subscriber rather than by message. If you open the same newsletter five times, you register as one opener. If you forward the email and your friend opens it, that still counts as you opening it — because the tracking is tied to the email address the message was sent to, not the device that loaded it.

What Data Does Substack Collect When You Open a Newsletter?

The tracking pixel captures several data points at the moment of open:

• Timestamp: The exact date and time of the open.
• Device type: Mobile or desktop.
• Email client: Gmail, Apple Mail, Outlook, and so on.
• Open count per subscriber: Whether this is a first open or a repeat engagement.

Beyond opens, Substack's link tracking creates unique URLs for each subscriber's email address, so every link click is individually attributable. The platform tracks which links you clicked, how often, and in what order.

What Can Writers Actually See About You?

Writers access two levels of data. At the post level, they see aggregate metrics: open rate as a percentage of subscribers, click rate, total link clicks by URL, and scroll depth for web views.

At the subscriber level, the picture is more detailed. The Substack dashboard includes a subscriber list with individual rows for each reader. Each row shows a five star activity rating — Substack's own metric for how engaged that subscriber has been in the past month, factoring in email opens and web views. Writers can also see per subscriber open history and click history.

This matters for a practical reason: a writer can identify low-engagement subscribers and clean their list, or segment their most active readers for paid conversion campaigns. Your reading behavior — which posts you opened, which links you clicked — directly shapes how a writer manages their list.

How Does Gmail's Image Proxy Change This?

Gmail has routed all email images through its own proxy servers since 2013. When Substack's tracking pixel fires in Gmail, the request reaches Google's infrastructure first, not Substack's server directly. Google strips your real IP address from the request, which means Substack cannot see your precise location or home network.

That protection is meaningful but limited. The open event itself still registers. Substack still learns that the pixel was fetched, when it was fetched, and which subscriber's email address triggered it. Google's proxy masks your geographic location and ISP — it does not prevent the open from being recorded.

In April 2026, Gmail made additional changes to how it handles tracking pixels in inbox rendering, which caused Substack open rates to dip noticeably across the platform. The episode confirmed that Gmail's proxy behavior directly shapes what Substack sees, but also confirmed that Substack tracks opens as a core platform feature, not an opt-in add-on.

Do Beehiiv, Ghost, and ConvertKit Track the Same Way?

Every major newsletter platform tracks opens by default. The mechanisms are functionally identical:

• Beehiiv uses tracking pixels and link click tracking, and its analytics dashboard gives writers estimated read time alongside open and click data. Beehiiv markets its analytics depth as a competitive advantage.
• Ghost Pro includes open tracking for newsletters sent through its managed hosting tier. Self hosted Ghost instances can be configured without tracking, which makes it the most privacy respecting option for readers who choose writers on that infrastructure.
• ConvertKit (now Kit) tracks opens and includes location data based on the IP address that loads the tracking pixel — making it more granular than Substack on geographic data, at least for non-Gmail users.

The implication: if you read newsletters in Gmail from any of these platforms, the same pixel-and-proxy dynamic applies. Gmail partially obscures your location. The open itself is always recorded. Link clicks are always fully attributable regardless of platform. For a deeper comparison of how email delivery providers handle tracking, see Is Mailgun Tracking Your Email?.

Why Email Privacy Advocates Should Care

Substack has positioned itself as the home of independent writers and reader-supported journalism. That positioning creates a trust gap: readers who have left ad-supported platforms to support writers directly may not expect to be tracked in ways that resemble the marketing email industry they were escaping.

The tracking is not incidental. It is core to how writers manage and grow their lists. Subscriber activity ratings, open histories, and click data drive decisions about list cleaning, content strategy, and paid conversion. Every newsletter you open without protection contributes behavioral data to a system you likely never knowingly opted into.

Substack's privacy policy discloses that it collects this data, but disclosure in a terms document most readers never read is not the same as informed consent at the moment of opening an email. For context on how this fits into broader patterns of newsletter tracking, see How to Detect Email Tracking Pixels in Gmail.

How to Block Substack Tracking Pixels in Gmail

Three approaches exist, with meaningfully different trade-offs:

• Native Gmail image blocking: Gmail's settings include an option to not automatically display images. This prevents the tracking pixel from loading, but it also breaks every image in every newsletter, making visually formatted posts unreadable. It's a blunt instrument that most readers abandon quickly.
• PixelBlock: A Chrome extension that blocks known tracking pixels while still loading non-tracking images. It works for straightforward pixel implementations but does not handle link tracking, and it requires manual updates as senders change their pixel domains.
• Gblock: A Gmail-specific privacy extension that blocks tracking pixels automatically, including those sent through Mailgun's infrastructure that Substack uses. Gblock distinguishes between tracking pixels and legitimate email images, so newsletter content loads normally while the 1x1 spy pixel is silently blocked. It also covers link tracking, which neither Gmail's native settings nor PixelBlock address.

The practical difference: with Gblock active, opening a Substack newsletter does not register as an open in the writer's dashboard. Your reading behavior stays private. The writer still receives your subscription fee if you are a paid subscriber — you are not withholding support, just withholding surveillance data.

Protecting Your Reading Privacy

Substack tracks email opens by design, and the data collected — timestamps, device type, email client, per subscriber engagement history — is available to writers in individual subscriber views, not just aggregate dashboards. Gmail's proxy reduces location exposure but does not prevent opens from being recorded. Beehiiv, Ghost, and ConvertKit operate identically.

For Gmail users, blocking Substack's tracking pixel requires a dedicated extension. Native Gmail image settings work but break newsletter formatting. Gblock handles the pixel silently while keeping newsletter content readable — which is the right trade-off for readers who want to support independent writers without being profiled in the process.