Want to write killer subject lines? Steal this prompt.

A reader took my research on email subject lines and created a custom headline maker (and even named it after me!)

Author

Brad Wolverton
December 16, 2024

👋🏻 Welcome to Newsletter Examples, where I highlight cool sh*t I’m seeing in newsletters that you can steal for your newsletter.

This week, I’m showing how Mark R. Hinkle of the AIE Network used my insights on effective subject lines to create a powerful headline-generating tool. Reading time: 3 minutes.

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Step 1: Gather inputs

A few years ago, I did an analysis of 750+ email subject lines at The Hustle. It was one of my most engaged threads ever.

Some of The Hustle’s winning subject lines (‘20-21)

Among other things, the analysis showed that:

  • Shorter is (almost always) better. The Hustle’s best subject lines averaged just 33 characters.

  • Boring isn’t always bad. One of the most-clicked emails (55% open rate) was headlined: “How bitcoin are created.”

  • If you help people make money, they’re apt to click.

  • Making declarative statements can also boost opens👇️…

Step 2: Create a prompt

Reader Mark Hinkle took that research, including actual winning subject lines from hundreds of A/B tests at The Hustle, and turned it into a ChatGPT prompt to help him write better headlines.

Below is the prompt he came up with:

  • Notice how he provided ChatGPT with a “role” and “objective”

  • You can use this prompt to improve your headlines (I copy/pasted the prompt here so you won’t have to retype it)

  • Feel free to tweak the prompt based on your own inputs and learnings

Step 3: Save your prompt

Hinkle, author of The AI Enterprise newsletter, one of my go-to AI newsletters, uses PromptDen’s PromptForge to save his prompts.

It allows him to replace the variables while preserving the examples he used in the few-shot prompt. “I just click a few buttons, and the prompt is rendered in ChatGPT,” he wrote in his Dec. 3 issue, where he shared this and other secrets from his “AI magician’s toolkit.”

Step 4: Create a GPT

But Hinkle took it one step further, codifying the prompt into a CustomGPT.

He basically built an Email Headline Making Machine, which he says works even better than the prompt.

He named it the Brad Wolverton GPT lol…and made a copy available for Newsletter Examples readers (you need a ChatGPT account to access it).

I asked Hinkle how Brad Wolverton GPT has performed for The Artificially Intelligent Enterprise, and he pointed to some impressive open rates (between 60.9% and 64.1%).

Here are some of the winning subject lines and preview text the GPT has come up with:

But even a so-called AI magician doesn’t use AI for every headline. In fact, he doesn’t use AI headlines at all in AI Tangle, another one of his newsletters, and its open rates are even higher (78% to 88.9%).

What’s the secret to those open rates?

“The big advantage,” Hinkle told me, “is my writer.”

Hope you enjoyed this week’s examples. I’ll be back next week with a new set!

☮️ -Brad

P.S. Congrats to readers Juliet Lyall and Ethan Brooks, who guessed where I took that gorgeous pic in the UK with my family. In case you’re wondering, it was Oxford.

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