Users enter when they subscribe to the purchase-signal list (the signal that they bought a Workers Paid plan). They receive M1 — Welcome on entry, wait 5 days, then receive M2 — Lesser-known features. Both milestone emails run an A/B subject-line test.
6722xwwq. Subscribing to this list is the signal that the user purchased a Workers Paid plan.Users flow top-down from a single Start (subscribe to the purchase-signal list), receive M1 — Welcome, wait through a 5-day delay, then receive M2 — Lesser-known features. Each milestone email carries an A/B subject-line experiment (the purple split nodes below).
Both emails ran a subject-line A/B test — same body, different subject. The variants and the read on why each performed are captured below to guide future upgrade and onboarding messaging.
In Iterable, A/B tests on journey emails are called Experiments. We run one on both milestone emails — subject lines only. Each optimizes for unique open rate (getting the developer back into the inbox to see what their plan unlocked).
| What's tested | Variant A | Variant B | Win condition | |
|---|---|---|---|---|
| M1 — Welcome | Subject line | "You're on the Workers Paid plan. Here's what it unlocks." | "You just upgraded. Here's everything that came with it." | Unique open rate |
| M2 — Lesser-known features | Subject line | "You unlocked more than higher limits. Here's what most developers miss." | "These paid features are already on your account. Most developers never find them." | Unique open rate |
"You're on the Workers Paid plan. Here's what it unlocks."
Developers respond to explicit, transactional framing. Suggests they want to know what changed on their account, not be sold to. Tells you future upgrade emails should lead with the plan name and a direct value statement.
"You just upgraded. Here's everything that came with it."
Conversational tone outperforms formal tone. Suggests developers respond better to language that acknowledges the action they just took rather than restating the plan name.
"You unlocked more than higher limits. Here's what most developers miss."
The curiosity gap works. "Most developers miss" creates tension on FOMO. Suggests developers are motivated by not wanting to leave value on the table.
"These paid features are already on your account. Most developers never find them."
Ownership framing outperforms the curiosity gap. Makes the value feel immediately accessible. Suggests future onboarding emails introducing the upgrade/purchase should lead with what they already have, not what they might be missing.
Primary metrics measure immediate message performance. Secondary metrics test whether informed users actually engage with — and retain on — the paid plan over time.