If you’re sending email campaigns and not testing your subject lines, you’re leaving easy wins on the table. This guide is for anyone using Vero who wants to run simple, no-nonsense A/B tests on subject lines—without getting lost in marketing fluff or overcomplicating things.
Whether you're new to Vero or just want to make your campaigns more effective, I'll walk you through setting up your first A/B test, what actually matters, and what you can skip.
Why Bother A/B Testing Subject Lines?
You get one shot for your email to stand out in an inbox. Most emails die unopened. Subject lines matter more than clever copy or fancy design. Testing lets you separate what works from what you think works.
But don’t expect miracles. A/B testing isn’t about magically doubling open rates overnight. It’s about slowly, steadily finding what your audience actually responds to, and making decisions based on data—not guesswork.
What You Need Before You Start
- A working Vero account (obviously)
- An email campaign ready to go (newsletters, promotions, whatever)
- At least a few hundred recipients (the more the better—small lists make tests noisy and results harder to trust)
- Two subject lines you want to test
That’s it. Don’t overthink this. If you’re still writing your campaign, keep the subject lines short, clear, and relevant.
Step 1: Come Up With Two (Good) Subject Lines
Don’t just slap together two random lines. You want a test that actually tells you something.
What to try: - One straightforward, descriptive line vs. one curiosity-driven or playful one - Personalization (e.g., with first names) vs. generic - Including an offer/number (“Save 20% today”) vs. no offer
What to ignore: - Testing tiny tweaks (“Newsletter #5” vs. “Newsletter #6”)—not worth your time - Overly complicated lines you’d never actually send
Pro tip: Write both subject lines before you go near Vero. Saves you from fumbling around in the editor.
Step 2: Set Up Your Campaign in Vero
Log in to Vero, and start creating your campaign as you normally would. Choose your audience, set up your email content, and get everything ready except for the subject line.
When you reach the subject line section, look for the option to “Add a variation” or “A/B test subject lines.” Depending on your version of Vero, this might be a little button or a dropdown.
How it works:
You’ll enter both subject lines here. Vero will split your audience—usually evenly—between the two versions.
Don’t get distracted:
- Ignore “A/B/C/D” testing unless you have thousands of recipients. More versions = slower, murkier results.
- No need to mess with advanced settings unless you have a real reason.
If you can’t find the A/B test option:
Double-check you’re in the right campaign type (Broadcasts and Newsletters support this; Transactional emails usually don’t). If it’s missing, check Vero’s docs or contact support. No shame in that.
Step 3: Choose Your Test Settings
Vero’s A/B testing for subject lines is pretty straightforward, but there are a couple of decisions to make:
1. Audience Split
- Default: 50/50 split (recommended)
- Manual: Some plans let you pick a “test group” and a “winner send” group. For most people, stick with 50/50. The “winner send” feature can be helpful for big lists (5,000+), but it’s overkill for smaller sends.
2. Winning Metric
- Open Rate: This is the only metric that makes sense for subject lines. Ignore clicks or conversions here—you want to know if people opened your email, not what they did after.
3. Test Duration
If you’re using the “winner send” feature: - Set a test duration (e.g., 2 hours after sending to the test group) - After the time is up, Vero sends the winning subject line to the rest of your audience
For most users: Ignore this. Just do a 50/50 split and look at the results later. It’s simpler, less prone to error, and you don’t have to guess how long your recipients take to open emails.
Step 4: Double-Check Everything
Seriously—don’t skip this. A/B tests are unforgiving if you make a typo or mix up which subject line is which.
Go through a checklist: - Are both subject lines spelled correctly? - Is the rest of the email set up and previewed? - Is your audience selected correctly? - Is the schedule correct? (If you’re scheduling a send)
If possible, send yourself a test email for each variant.
Pro tip:
Write down which subject line is “A” and which is “B” somewhere. Vero’s reporting is usually clear, but you don’t want to mix them up later.
Step 5: Launch Your Campaign
Hit send. That’s it. Vero will handle splitting the audience and tracking which subject line each recipient got.
No need to watch your screen like a hawk. The test runs automatically.
Step 6: Wait for Results (Impatience Is Your Enemy)
Don’t rush. Most people who will open your email do so in the first few hours, but not everyone. Give it at least 24 hours—more if your audience is global or opens emails slowly.
What to ignore: - Micro-analyzing results after 30 minutes - Making decisions based on a handful of opens
The more recipients you have, the more confident you can be in the results. If you have a tiny list (under 500), treat results as a directional hint, not gospel truth.
Step 7: Review the Results in Vero
After enough time has passed, head to your campaign reports in Vero. You’ll see open rates for each subject line.
What to look for: - Is there a clear winner? (5%+ difference is usually worth acting on) - Are the results close? (If it’s neck and neck, it doesn’t really matter—pick either, or try new lines next time) - Did you get enough opens for the result to be meaningful? (If you got 10 opens on each, don’t read too much into it.)
Going Deeper (But Not Too Deep)
- Segment results: If you have a big, diverse audience, you can dig into how different segments responded. But for most people, just look for obvious patterns.
- Statistical significance: Don’t get obsessed. Unless you have thousands of recipients, you’re not doing scientific research. Use common sense.
Step 8: Apply What You Learned (Then Move On)
If you saw a clear difference, use the winning style for your next campaign—but don’t just repeat the same test forever. Keep testing new ideas.
What’s worth repeating: - Testing big, meaningful differences (tone, personalization, offer) - Building on what works—but mixing it up
What to ignore: - Chasing small wins (“Should I use a question mark or not?”) - Overfitting to one test (audiences and moods change)
Pro tip:
Keep a simple spreadsheet or notes of what you’ve tested and what worked. Over time, you’ll see patterns. Or you’ll realize half your “great ideas” actually flopped. Both are useful.
Common Pitfalls (and How to Dodge Them)
- Testing too many things at once: Stick to two subject lines. Adding more just muddies the water.
- Judging too fast: Give your campaign time. Don’t declare a winner after ten minutes.
- Overcomplicating: Fancy subject lines aren’t always better. Simple, clear, and honest usually wins.
- Ignoring context: What works for a flash sale won’t work for a newsletter. Test in context.
Wrapping Up: Keep It Simple, Keep Testing
A/B testing subject lines in Vero isn’t rocket science, but it’s easy to get distracted by unnecessary features or over-analyze minor differences. Start small. Test things that actually matter. Learn, adjust, and move on.
Email’s a long game. The only real mistake is assuming you “know what works” and never testing at all.
Go set up your next test. You’ll be surprised what your audience actually clicks on.