So, you want to get more people to open your emails. You’ve heard that tweaking the subject line is the way to go, but you’re tired of guessing—and frankly, tired of advice that boils down to “just be more engaging!” This guide is for you. We’ll walk through how to actually use AtozEmails to run A/B tests on subject lines, spot what works, and avoid wasting time on stuff that doesn’t matter.
Why Subject Lines Deserve Real Testing
Subject lines are the front door to your emails. If they’re weak, nobody comes in. But let’s be honest: most “best practices” for subject lines are recycled tips that work until everyone uses them. Emojis, personalization, urgency—they can help, but not always. The only way to know what works for your audience is to test, not trust someone’s LinkedIn post.
A/B testing lets you send two (or more) versions of your subject line to small groups, then pick the winner for the rest of your list. It sounds simple, but the details make all the difference.
Step 1: Get Set Up in AtozEmails
Before you try A/B testing, make sure you’re actually sending emails through AtozEmails—no, really, it’s worth double-checking. Their A/B testing tools only work if you’re using their campaign system, not just importing lists or automations from somewhere else.
What you need: - An AtozEmails account (obviously) - A list or segment that’s big enough for testing (at least a few hundred contacts; more is better) - A campaign you want to send—this won’t work for drip automations or transactional emails
Pro tip: If your list is under 200 people, don’t bother. The stats will be all over the place and you’ll end up chasing noise.
Step 2: Draft Your Subject Lines (No, Don’t Overthink It)
You need at least two subject lines for a proper A/B test. Here’s what actually matters: - Make each subject line different enough to matter. Small tweaks like “Hi, John” vs. “Hey, John” won’t show a real difference. - Focus on one variable at a time (humor vs. urgency, short vs. long, with/without emoji, etc.). - Don’t write ten versions—start with two or three max.
What to ignore: Obsessing over “power words” or trying to reverse-engineer viral subject lines. Your audience isn’t everyone else’s.
Quick examples: - Version A: “Your June statement is ready” - Version B: “Important: Review your June statement now”
Step 3: Set Up the A/B Test in AtozEmails
Here’s how to actually do it in AtozEmails:
- Create a new campaign.
- In the subject line box, look for the “A/B Test” or “Split Test” button—usually a small icon next to the subject line field.
- Enter your two (or three) subject lines. AtozEmails will automatically create variants.
- Decide what percentage of your audience gets each version. Most people stick with:
- 20% get version A
- 20% get version B
- 60% get the winner (after the test period)
- Choose how long the test should run before picking a winner. AtozEmails lets you pick from 1 hour up to 24 hours. Shorter is better for time-sensitive campaigns, but longer gives better data.
Pro tip: If your emails go out at odd hours, set the test to run during your audience’s peak open times.
Step 4: Pick Your Winning Metric (Don’t Just Default)
AtozEmails usually defaults to “open rate” as the winning metric. That’s fine—if your only goal is to get more eyes on your email. But sometimes, what matters is clicks, not just opens.
- Use open rate if your content isn’t super clickable (newsletters, announcements).
- Use click rate if you want action (sales, signups).
- Ignore “reply rate” unless you’re in B2B sales or personal outreach—most people won’t reply.
Reality check: Open rates have gotten less reliable since Apple and Gmail started auto-opening emails. If your test numbers seem weirdly high or tied, switch to click rate.
Step 5: Launch and Let the Test Run
Hit send. AtozEmails will send your variants to the test groups, then automatically send the winning version to the rest of your list after the test window.
Don’t meddle: Resist the urge to “peek” and restart if your favorite subject line isn’t winning. The whole point is to trust the data.
Common mistake: Announcing a winner after an hour because you’re impatient. Unless your campaign is truly urgent, let the test run at least 4-6 hours—overnight is even better.
Step 6: Review Results (And Don’t Read Into Every Blip)
After the campaign, AtozEmails shows you which subject line won, by how much, and the raw numbers. Here’s what to actually look for: - Statistically significant difference: If one subject line wins by a few percent, it might just be luck—especially on smaller lists. - Big gaps (>8-10%) usually mean a real winner. - Weird spikes or ties: Sometimes, neither line is a clear winner. Don’t force a lesson where there isn’t one.
What not to do: Don’t write a blog post about your “findings” after a single test. Patterns only show up after multiple campaigns.
Step 7: Apply What You Learn—But Keep Testing
If a subject line style works, use it again—but don’t assume it’s magic. Audiences get bored fast. Keep testing, but don’t obsess. Most improvements are small and add up over time.
A/B testing isn’t a set-and-forget tool: - Keep a simple doc or spreadsheet with your subject line test results. - Note what you changed, and what actually moved the needle. - Every few months, look for patterns, not just one-off wins.
Ignore: The urge to test every single send. Save your energy for bigger campaigns or when you’re trying something new.
What Works, What Doesn’t, and What to Skip
Works: - Testing boldly different subject lines (short/long, question/statement, emoji/no emoji) - Letting tests run their full time - Focusing on one variable at a time
Doesn’t work: - Tiny tweaks (changing one word) - Testing on tiny lists - Caring too much about “industry benchmarks”
Skip: - Overcomplicating with multivariate tests (unless you have a massive list and lots of time) - Writing subject lines for algorithms, not humans
Pro Tips for Getting More Out of AtozEmails
- Segment your list: Results on your whole list might hide what works for different groups. If you have time, test on your best segments.
- Check deliverability: Spammy words or too many emojis can hurt your overall deliverability, even if open rates tick up for one test.
- Don’t chase trends: “Personalization” works until your audience gets bored. Keep it fresh.
Keep It Simple, Keep Going
A/B testing subject lines in AtozEmails isn’t rocket science, but it does take some discipline. Don’t get hung up on finding “the perfect line.” Focus on running real tests, making honest observations, and moving on. Most wins are small and build up over time. Keep it simple, keep testing, and remember—nobody remembers a subject line except you.