Most subject lines are forgettable. They either oversell, say nothing at all, or default to “Newsletter #24.” That's a fast track to the Promotions tab.
Before 👉 After: subject line upgrades
Small changes can turn a “meh” subject line into one that stops the scroll. Here's how to apply the curiosity, numbered, and benefit-led styles in real life:
Curiosity hook
- ❌ Instead of: “Our Product Update”
- ✅ Try: “The new feature our customers swear by”
Why? Teases the value without giving it all away and makes them want to click to find out.
Numbered tease
- ❌ Instead of: “Our August Newsletter”
- ✅ Try: “3 ways to get more sales this month”
Why? Numbers promise clear, digestible takeaways - proven to lift opens.
Benefit-led
- ❌ Instead of: “Big Sale Now On”
- ✅ Try: “48 hours to save on our most-loved picks”
Why? Leads with the benefit (saving on what they love) and adds urgency.
Now, pick your champion.
Write 2 variations for each campaign using the framework above, test them with 20% of your list and let the data decide. A clear open rate winner after a 4-hour window? Roll it out to the rest and watch your open rate skyrocket.
Here's how:
Next time you build a campaign in Klaviyo: