We've watched enough dunning email A/B tests to develop strong opinions. Here are the twelve rules that keep winning, ranked by impact.
# 1. Say what happened in the subject line
Bad: "Action required" · "Your account" · "Update needed"
Good: "Your Notion payment didn't go through" · "Your card ending 4242 was declined"
Vague subject lines get opened by the wrong people (curious, but not the cardholder). Specific ones filter for the person who can actually fix the problem.
Lift: +18% open rate, +11% click rate on step 1.
# 2. Never lead with a threat
"Your account will be canceled" as an opener converts worse than "Your dashboards are still running — here's how to keep them that way." The first triggers loss aversion and defensiveness. The second triggers "oh right, I need to handle this."
Save escalation language for step 4, if at all.
# 3. One button. One link. One thing.
Every extra CTA halves click-through on the primary one. The primary CTA on a dunning email is Update payment method. Not "Learn more." Not "Contact support." Not "See invoice." Not "Manage subscription."
Everything else lives below a --- in tiny gray text.
# 4. Use the customer's actual product context
"Your workspace Acme Marketing and its 14 dashboards are affected" converts substantially better than "Your account is affected." AI makes this trivial to generate at scale.
# 5. Show the amount, but not the full invoice
"$149 monthly" in the email is fine. Rendering a full invoice inline is not — it makes the email look like a bill, not a helpful nudge.
# 6. Match tone to failure reason
- Insufficient funds → warm, no-blame, "these things happen"
- Expired card → routine, "quick update needed"
- Hard decline → concerned, "your bank flagged this, likely nothing wrong on your end"
- 3DS challenge → clear, "one tap to confirm it's you"
Same customer, four different tones. Same customer, four different recovery rates.
# 7. Send from a human
[email protected] recovers less than [email protected]. The uplift isn't huge (2–4%), but the reply quality is dramatically better — and those replies are where retention conversations happen.
# 8. Reply-to a monitored inbox
If you send from a person, that person (or a small team) must actually read replies within a business day. Automated "do-not-reply" recovery mail signals "we don't care" at the exact moment you need to signal the opposite.
# 9. Timing beats copy at the margin
A great email at the wrong time loses to a mediocre email at the right time. Send:
- Weekdays 9–11am customer local time, not your local time.
- Never Friday afternoon.
- Never on customer's local holidays (calendar API is your friend).
# 10. Keep step 1 short. Really short.
Under 60 words. One sentence explaining what happened, one sentence with the fix, one button. Longer emails get scanned once and closed. Short ones get acted on.
# 11. Step 2 explains, step 1 nudges
By step 2 (24h later), the customer either didn't see step 1 or hasn't gotten around to it. This is where you add context:
- What features are still working
- What will stop working, when
- How to pause instead of losing access
- A human name and reply invitation
# 12. Never bury the pause option
If your product supports pause/downgrade, offer it explicitly by step 3. Losing a $99/mo customer to $0 is worse than keeping them at $29. AI copy that sounds like it's on the customer's side — not the company's — is what makes this land.
# What we no longer bother with
- Countdown timers ("cancels in 47:29:04"). Feels desperate, works short-term, hurts long-term.
- Gifs and images in dunning mail. Slower to load, more likely to be spam-filtered, no conversion lift.
- "PS." tricks. They worked in 2018. They don't now.
- Alt-language versions unless you have real translation. Bad Spanish is worse than English.
# The one-line summary
Help the customer solve their problem in the fewest possible taps. Everything above is a corollary.