2023: Substack Launches Notes, Blurring the Line Between Email and Social

On April 5, 2023, Substack CEO Chris Best published a blog post announcing Notes — a new feature that would let Substack writers and readers post short-form content in a public feed. The feature looked familiar. It had a feed. It had likes (called “restacks”). It had replies. It had a discover tab. It looked, in other words, a lot like Twitter.

The timing was not subtle. Twitter, now rebranded as X under Elon Musk’s ownership, was in the middle of its most turbulent period. Writers and journalists who had used Twitter as their primary discovery and engagement platform were actively seeking alternatives. Substack, which had quietly become one of the most important email newsletter platforms on the internet, was making a bid to capture the social activity that was fleeing Twitter — and to build something genuinely new in the process.

Notes represented a fascinating experiment: what happens when you build social media features on top of an email platform instead of the other way around?

The Context: Email-First, Social-Second

To understand why Notes mattered, you need to understand what Substack had already become by early 2023. Founded in 2017 by Chris Best, Hamish McKenzie, and Jairaj Sethi, Substack had grown from a simple newsletter hosting tool into a platform with over 35 million active subscriptions. Top writers on the platform earned hundreds of thousands — in some cases, millions — of dollars per year from paid newsletter subscriptions.

Substack’s core product was straightforward. Writers published long-form content. That content was delivered to subscribers’ email inboxes and simultaneously published on the writer’s Substack web page. Readers could subscribe for free or pay for premium content. Substack took 10% of paid subscription revenue.

The model worked because it was built on email’s fundamental strengths: direct delivery, ownership of the subscriber relationship, and independence from algorithmic feed manipulation. When a Substack writer hit “publish,” every subscriber received the full post in their inbox. No algorithm decided who saw it. No platform change could throttle its reach. The email list belonged to the writer, not to Substack — writers could export their subscriber list and leave at any time.

But Substack had a discovery problem. Finding new newsletters to subscribe to was difficult. Writers relied heavily on external platforms — primarily Twitter — to promote their Substacks and attract new readers. When Twitter became unstable, Substack’s external discovery channel was threatened.

What Notes Actually Was

Notes launched as a feed of short-form posts displayed within the Substack app and website. Writers could post text, images, and links — much like a tweet. Readers could like posts, “restack” them (Substack’s equivalent of a retweet), and reply. The Notes feed was algorithmically curated, showing posts from writers you subscribed to alongside recommended content from the broader Substack network.

The key architectural decision was that Notes was built on top of the existing newsletter subscription graph. If you subscribed to a writer’s newsletter, you automatically saw their Notes. If you followed a writer on Notes, you were prompted to subscribe to their newsletter. The social layer and the email layer were deeply integrated, each feeding the other.

This was fundamentally different from how social media and email had historically interacted. On Twitter, a writer might tweet a link to their newsletter with a “subscribe” call to action. The social platform and the email platform were separate systems, connected only by links. On Substack, the social activity and the email activity happened within the same ecosystem, sharing the same subscriber relationships.

The Twitter Connection

Substack did not hide the fact that Notes was a response to the Twitter situation. The launch came at a moment when writers were actively mourning the Twitter they had once loved and seeking new homes for the conversations that had previously happened there.

The reaction from Twitter/X was swift and hostile. Within days of the Notes launch, Twitter began throttling links to Substack posts. Tweets containing Substack links received reduced distribution. For a period, Twitter blocked the ability to like or retweet posts containing Substack URLs. Elon Musk publicly criticized Substack, and the platform was briefly treated as a competitor to be suppressed rather than a content source to be linked.

The conflict highlighted a fundamental tension. Twitter viewed Substack as a competitor siphoning away its writers and their engagement. Substack viewed Twitter as an unreliable discovery channel that it needed to replace with its own social features. The episode demonstrated, once again, the fragility of building an audience on a platform you do not control — the exact problem that email newsletters were supposed to solve.

Blurring the Boundaries

Notes represented something genuinely new in the relationship between email and social media. For the first time, a major platform was integrating both formats into a single product, using each to strengthen the other.

The social feed drove newsletter discovery. Writers who posted engaging Notes attracted new subscribers to their email newsletters — subscribers who might never have found them through email alone. The Notes algorithm could surface writers to potential subscribers based on interests and engagement patterns, solving the discovery problem that pure email platforms had always struggled with.

The newsletter drove social engagement. Writers with large, engaged email subscriber bases had built-in audiences for their Notes. A writer with 50,000 newsletter subscribers had 50,000 potential readers for every Note they posted, giving them a social audience without having to build one from scratch on a separate platform.

This integration challenged the conventional wisdom that email and social media were fundamentally separate channels requiring separate strategies. Substack was suggesting that the two could be woven together, with email providing the direct, owned relationship and social features providing the discovery, conversation, and community elements that email alone had always lacked.

The Broader Implications

Substack was not the only company exploring this intersection. Beehiiv, another newsletter platform, had added community features. Ghost had been building social-like recommendation features. ConvertKit (now Kit) was developing creator network features. The newsletter platform category was collectively moving toward adding social discovery layers on top of email-first products.

This trend represented an important shift in how the industry thought about email. For decades, email and social media had been treated as separate channels with separate strategies. Email was for retention and conversion. Social was for awareness and discovery. The two were connected by links and calls to action but operated as fundamentally different experiences.

The Substack Notes model proposed a merger: what if the same platform handled both discovery (social) and delivery (email), with the subscriber relationship as the connecting tissue? What if you did not need Twitter or Instagram or TikTok to find your audience — what if your newsletter platform could handle that too?

What It Meant for Email

Notes did not diminish email’s importance within the Substack ecosystem. If anything, it reinforced it. The email newsletter remained the core product — the thing that subscribers paid for, the thing that writers spent most of their time creating, and the thing that generated revenue. Notes was a complementary layer that enhanced the email experience without replacing it.

The newsletter still arrived in subscribers’ inboxes. The direct relationship between writer and reader still ran through email. The subscriber list still belonged to the writer. Email’s fundamental value propositions — direct delivery, ownership, portability — remained intact and central.

What Notes added was a solution to email’s oldest weakness: discoverability. You cannot discover a new newsletter by opening your inbox. You discover newsletters through recommendations, social sharing, search, and word of mouth. By building a social discovery layer directly into the newsletter platform, Substack was addressing a gap that email alone could never fill.

The Experiment Continues

As of 2026, the Substack Notes experiment has produced mixed results. The feature has attracted meaningful engagement from the Substack community, particularly among writers and politically engaged readers. However, it has not replaced Twitter/X as the primary public conversation platform for most writers. The network effects that make social platforms valuable take years to build, and Substack’s user base, while large for a newsletter platform, is small compared to major social networks.

What Notes has demonstrated is that the boundary between email and social media is more permeable than previously assumed. The two formats are not opposites — they are complementary, and platforms that integrate both intelligently can offer writers and creators something that neither format provides alone.

For email marketers, the lesson is practical: email remains the foundation, but discovery and community features are increasingly important complements. Build your email list as your core asset, but do not ignore the social and community layers that help that list grow.

Start building your email foundation with our ROI Calculator to understand what your subscriber list is worth, and use our Subject Line Grader to make sure every newsletter earns its opens.

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Frequently Asked Questions

What is Substack Notes?

Substack Notes is a short-form social posting feature launched by Substack in April 2023. Similar to Twitter/X, it allows Substack writers and readers to post short text updates, share links, and engage in public conversations. Unlike standalone social platforms, Notes is integrated with Substack's newsletter infrastructure, meaning a writer's email subscribers can see their Notes and vice versa.

Why did Substack launch Notes?

Substack launched Notes primarily in response to the chaos at Twitter/X following Elon Musk's acquisition in late 2022. Many writers who used Twitter for audience discovery and engagement were looking for alternatives. Substack saw an opportunity to capture that activity within its own ecosystem, keeping writers on-platform for both long-form newsletters and short-form social engagement.

Does Substack Notes replace email newsletters?

No. Substack Notes is a complementary feature, not a replacement for newsletters. Writers still publish long-form content as email newsletters that are delivered to subscribers' inboxes. Notes adds a public, social layer on top of the email-first platform. The two formats serve different purposes: newsletters for in-depth content delivery, Notes for discovery, conversation, and community building.