The Morning Brew Subject Line Formula
How a newsletter grew to 4M subscribers using a curiosity-gap-and-payoff formula in every subject line — and why it doesn't feel like clickbait.
Read the source — then read the reveal.
Names the topic ('Apple acquisition'), names the gap ('a startup nobody's heard of') — without giving the answer. Maximum curiosity in 11 words.
The specific number signals 'reported, sourced, real' instead of 'rumor'. The reader trusts the gap because the surrounding details are crisp.
The preview line gives away three useful payoffs for free. By the time the reader hits 'subscribe', they've already received value.
The opening sentence converts the curiosity into a concrete future-prediction promise. Not 'an interesting story' — a specific insight you'll have after 90 seconds.
Steal it. Use it tonight.
- 1Subject line formula: Topic + specific detail + withheld insight, in under 12 words.
- 2Use the preview text as a free reciprocity gift — don't waste it on 'In this newsletter…'
- 3Open the first line with a concrete prediction or claim that pays off the subject's tease in 60 seconds.
- 4Use one emoji as a sender brand mark, not as decoration. Consistent, not cute.
The curiosity-gap-without-payoff trap. If the body of the email doesn't deliver the specific insight the subject teased, your open rate decays faster than any other metric in email.