Exclusive: Substack continues its acquisition streak with public correspondence startup Letter

It’s not clear whether Letter will be used to allow Substack writers to collaborate with one another, with their readers, or both. McKenzie declined to offer a firm list of ways that Letter will be integrated into Substack’s platform, though he noted that some of Substack’s most popular writers already use their newsletters to engage in dialogue with their readers. The writer Zeynep Tufekci, for example, solicits arguments against her positions, then features the most persuasive responses in a regular feature in her newsletter called The Counter. Tufekci pays people for them. 

At minimum, Letter should provide a clean and easy way for Substack authors to debate one another. “The central pitch [of Letter] is that there’s a real dearth of long-form conversation [online],” Letter cofounder Clyde Rathbone said. “There’s very little true dialogue.”

The Letter acquisition is the latest in a string of moves and investments Substack has made to support its writers. In addition to a legal defense fund, Substack Defender, a curriculum of online courses, called Substack Grow, and a Slack channel it built in-house, in May the startup acquired People & Company, an audience and community management consultancy, in hopes of helping its writers build community with their audiences. 

“The idea is that you’re not having to figure out everything by yourself,” McKenzie said. “We’ve always thought that it’s not enough to offer some disparate tools. We’re setting about building an entire infrastructure [to support writers].”

That process, McKenzie stressed, is in an early stage. “We’re primitive on everything,” he said.

These investments complement Substack’s better-publicized effort to attract writing talent. The platform recently won a clutch of headlines — positive and negative — for paying six-figure advances to writers (and, more recently, podcasters) to start writing on its platform.

The services and features it’s been investing in may keep some of that A-list talent around. But crucially, the hope is that it will convince more of the platform’s writers to invite their friends over as well. “Our best way of getting writers is through referrals,” McKenzie said.