Flodesk recently added built-in A/B testing for subject lines. And if you’ve been curious about it, this is the practical walkthrough you need.
What Flodesk’s A/B testing does (and doesn’t do)
Flodesk’s A/B testing is built specifically for subject lines on email campaigns. You write two versions, Flodesk splits your audience, and after 24 hours the subject line with the better open rate wins. If your list is large enough, the winning subject line is automatically sent to the remaining recipients who haven’t received the email yet. Flodesk handles all the splitting and timing for you.
A few things worth knowing upfront:
- The winner is determined by open rate only. Click rate appears in your analytics for reference, but it doesn’t affect which subject line wins.
- You can only test two subject lines at a time.
- This feature is available for email campaigns, not workflows.
If your list is under 300 recipients, the feature works slightly differently. Both subject lines go out to your full audience right away (split evenly), and after 24 hours, you’ll see which performed better. But there’s no waiting group to send the winner to. You still get the data; you just don’t get the automatic winner send.
What actually makes a good subject line test
The most useful tests compare two approaches that are genuinely different in strategy, not just wording. If your two subject lines are both short, friendly, and curiosity-driven, you’re not going to learn much. Even if one outperforms the other.
Here are a few angles worth testing:
Curiosity vs. directness: “Your May workflow checklist is here” vs. “Stop sending emails nobody opens”
With emoji vs. without: “Three things to set up in Flodesk before you launch 🚀” vs. “Three things to set up in Flodesk before you launch”
Personalisation vs. none: “[First name], your welcome sequence needs this” vs. “Your welcome sequence needs this”
Specific vs. intriguing: “How to set up Flodesk segments the right way” vs. “The Flodesk mistake that’s costing you opens”
The goal is to learn something about what resonates with your specific audience. Not just to find a winner for this one email.
The honest truth about small lists
If you have a smaller list, A/B testing is still worth doing. But your expectations need to shift.
With a small sample, a difference of a few percentage points in open rate could easily be random. One person who opened on a whim can swing your results. That doesn’t mean the data is useless; it means you’re building a picture over time, not drawing conclusions from a single test.
The most useful thing you can do with a small list is keep a simple record of what you test and what wins. Over five or six tests, patterns tend to emerge. Your audience responds to a certain tone, a certain type of subject line, a certain kind of specificity. That pattern is more reliable than any single result.
How to read your results
Your A/B test results live in the Email report page in Flodesk, in the A/B test section. After the 24-hour window closes, you’ll see both subject lines side by side with open rate and click rate for each, plus which one won.
A few things to note when you’re reading them:
Open rates can shift after the 24-hour window. Flodesk determines the winner at the 24-hour mark, but the analytics continue to update as opens come in. Don’t be surprised if the gap changes slightly over the following day or two.
A close result (say, 28% vs. 31%) is interesting data, but it’s not a landslide. A wider gap tells you something more definitive about what’s working.
Ties go to Subject Line A. If both subject lines have the exact same open rate when the 24-hour window closes, Flodesk sends Subject Line A to any waiting recipients. It’s rare, but worth knowing.
Applying what you learn
A single A/B test gives you a data point. A pattern across several tests gives you insight.
After each test, note what you tested, what won, and by how much. Over time, you’ll start to see whether your audience tends to respond to questions or statements, long or short, specific or mysterious. That knowledge makes every future subject line decision easier, and more effective.
Want help making sense of your results?
If you’ve run your first A/B test and you’re not sure what to do with what you’re seeing, or if you want a second set of eyes on your email strategy before you start testing, that’s exactly what a 1:1 Flodesk training session is for. We can dig into your analytics together and figure out what your audience is actually telling you.
