Proof · List growth · 90 days
Three small changes, 4,700 new subscribers
By June Park, Audience Data Analyst · Published June 24, 2026 · Updated July 26, 2026 · Client anonymized; figures representative of the engagement
A quarterly book-box subscription with a 15,000-profile list had a growth problem that looked like a traffic problem. It was not. Site traffic was healthy; the signup popup converted 1.1% of visitors, roughly half the 2.1% industry average in Omnisend's analysis of 1.24 billion popup displays. The form was leaking most of a year's growth before anyone saw an email.
The problem: a form built by committee
The baseline popup asked for five fields, fired the instant the page loaded, and offered 10% off. Each choice is defensible alone; together they underperformed. Omnisend's data shows immediate-fire popups converting at 1.9% versus 2.4% with a 6-to-10-second delay, and the desktop-designed layout was converting mobile visitors, 68% of the brand's traffic, at well under the 2.2% mobile-optimized benchmark.
The approach: test the levers the data says matter
We changed three things over two test cycles, measuring each against the prior cell. Fields went from five to two: email and first name. Timing moved to an 8-second delay. And the offer swapped from a 10% code to entry into a monthly sample-box drawing, which fit how the audience thinks: readers wanted the surprise box, not a coupon.
Channel work ran alongside. Audience research showed the buyer profile concentrated in a handful of book podcasts and two large reading subreddits, so partnership placements went there instead of broad social ads. New-cohort engagement by source was reviewed monthly, and one channel got cut for delivering signups that never clicked.
The result: growth that stays engaged
| Metric | Baseline | Day 90 |
|---|---|---|
| Popup conversion rate | 1.1% | 3.8% (industry avg: 2.1%) |
| New subscribers | — | +4,700 |
| Welcome flow revenue per recipient | $1.45 | $2.30 (category avg: $2.65) |
The welcome-flow number is the quality check. New subscribers from the rebuilt form and researched channels spent more per recipient than the old cohorts, closing on Klaviyo's $2.65 category average from 55% below it. Growth that arrives engaged compounds; growth that arrives cold becomes the dead weight we end up suppressing in audience rebuilds.
The full playbook, benchmarks included, is in the List Growth service and the list growth benchmarks guide.