Guide · subject lines
Dunning email subject lines, by step and reason
The subject line decides whether the email gets opened at all. The rule: say what happened, name your product, skip the alarm words.
Three rules
- Name the product. The customer pays several subscriptions; “Your payment failed” alone is anonymous and looks like phishing.
- Say it plainly. “didn't go through” reads as fixable; “URGENT” and “FINAL WARNING” read as spam.
- Keep it short. Mobile inboxes cut subject lines early; put the product name first when you can.
Day 0 (first notice)
- Your Acme payment didn't go through
- Payment failed: $49 for Acme
- A quick card update for Acme
- Acme: we couldn't charge your card
Day 1 and 3 (reminders)
- Quick reminder about your Acme payment
- Reminder: $49 still due to Acme
- Still pending: your Acme subscription
- Acme: one minute to update your card
Day 5 (final notice)
- Keeping your Acme account open
- Last notice: Acme will be paused
- Before we pause your Acme account
- Acme: last reminder about $49
By decline reason
- Expired card: Your card on file for Acme has expired
- 3-D Secure: Your bank needs you to confirm the Acme payment
- Insufficient funds: Your Acme payment will be retried
- Generic decline: Your bank declined the Acme payment
SaveMyMRR writes the subject for each step and reason automatically, in the tone you choose (friendly or direct).