If your email subject lines aren’t getting people to open, you’re shouting into the void. This guide is for anyone who wants to actually find out what works — not just guess. We’ll walk through setting up A/B tests for subject lines in Mailforge, break down where people mess up, and share shortcuts that save time. If you want real answers and fewer headaches, read on.
Why Bother A/B Testing Subject Lines?
Let’s be blunt: most subject lines stink. Even when they sound clever, half the time nobody clicks. The only way to know what works for your audience is to test. A/B testing shows you, with real numbers, which subject line actually gets more eyes on your emails.
But here’s what A/B testing won’t do: - Magically triple your open rates overnight. - Tell you why a subject line worked (it just shows you that it worked). - Replace thinking carefully about your audience.
If you’re hoping for a silver bullet, you’re going to be disappointed. But if you want to improve steadily and stop guessing, A/B testing is the best tool you’ve got.
Step 1: Get Your List and Email Ready
Before you jump into the Mailforge dashboard, pause for a second. You need: - An email list with at least a few hundred recipients (the more, the better). - A single email campaign you want to test subject lines on. - Two or more subject lines you’re willing to test (don’t overthink it).
Pro tip: If your list is under 500 people, don’t expect statistically bulletproof results. You’ll still learn something — just don’t bet the farm on the winner.
Step 2: Come Up with Two (or More) Subject Lines
This is where most people freeze. Don’t. Subject lines don’t have to be perfect. They just have to be different enough to tell which one works.
What to try: - Short vs. long subject lines - Questions vs. statements - Including a number or a date (e.g., “3 ways to fix X” or “Don’t miss June’s update”) - With vs. without emoji (test it — don’t assume)
What not to do: - Test two subject lines that are basically the same (“Your invoice is ready” vs. “Your invoice is now ready” — waste of time) - Get too clever. If you’re not sure what it means, neither is your reader.
Write your two (or more) options down somewhere handy.
Step 3: Set Up an A/B Test in Mailforge
Now for the nuts and bolts. Mailforge makes this pretty painless, but the details matter.
-
Create a new campaign
Log in and start a new campaign as usual. Pick your email list. -
Find the A/B Test Option
When you get to the subject line field, look for a button or link that says “A/B Test” or “Add variation.” (Mailforge sometimes moves UI elements, so poke around if you don’t see it.) -
Enter Your Subject Lines
Plug in your two (or more) subject lines. Mailforge will show you a split — usually 50/50 for two, or divided evenly if more. -
Set Your Test Size and Winner Logic
- Test size: Decide how much of your list gets the test versions. With small lists, just test on everyone. With big lists, you can send the test to a subset (say, 20% get version A, 20% get B, and the rest get the winner later).
-
Winner logic: Choose how Mailforge picks the winner. Usually, it’s based on open rate over a set period (e.g., 4 hours after sending). Set it and forget it.
-
Finish Email Content
The rest of your email stays the same for all subject lines. Don’t change the body copy — you want your results to be about the subject line, not the content. -
Review and Schedule/Send
Double-check your settings. Schedule or send your campaign.
Heads up: If you’re not sure which settings to pick, just split your whole list and send both versions at once. Don’t let fiddly options paralyze you.
Step 4: Wait for Results (Don’t Jump the Gun)
The hardest part: waiting. Give your test at least a few hours — ideally 24 — to collect enough data. Don’t declare a winner after 10 minutes.
What to watch for: - Open rate: This is the main metric for subject line tests. - Statistical significance: Mailforge usually shows if a winner is clear. If the difference is just a handful of opens, don’t overthink it. - Weird spikes: If you see a crazy-high open rate, double-check your email content — sometimes security bots “open” emails and mess with stats.
Step 5: Read the Results (Without Fooling Yourself)
Once the test is done, Mailforge should show you which subject line performed better. But, don’t fall into these traps:
- Assuming it’ll always work. One test doesn’t mean you’ve found the holy grail. Your audience, timing, and even random luck can all play a role.
- Chasing tiny differences. If A got a 29.8% open rate and B got 30.2%, that’s basically a tie.
- Ignoring the “why.” The numbers don’t tell you why people opened your email. Use common sense, and don’t be afraid to ask real people what caught their eye.
If you’re happy with the winner, use it as your new default — until you test again.
Step 6: Rinse, Repeat, and Don’t Get Fancy
The best email marketers don’t run one test and call it a day. They: - Run regular A/B tests (once a month is plenty for most folks). - Try bold, obvious differences (not tiny tweaks). - Don’t waste time on “best practices” that don’t actually work for their audience.
Stuff that doesn’t matter as much as you think: - Perfect grammar (sometimes a typo gets more opens — not that you should aim for them). - Using “Re:” in your subject line (it’s overdone and can backfire). - Fancy personalization, unless your list is really engaged.
Stick to clear, honest subject lines. Test things your gut says might work, and let the numbers do the talking.
Pro Tips and Common Pitfalls
- Don’t just copy what big brands do. Their audience isn’t yours.
- Test at different times of day. Mornings vs. afternoons can change open rates.
- Don’t obsess over tiny wins. If it’s not a clear difference, move on.
- Keep your test simple. The more variables you add, the less you’ll learn.
What to ignore: - Any “guaranteed” subject line formula. - “Growth hacks” that sound too good to be true. - Advice that doesn’t fit your brand or audience.
Wrapping Up
A/B testing subject lines in Mailforge isn’t magic, but it beats guessing every time. Focus on simple, meaningful tests and don’t get bogged down in the weeds. Run a test, look at the numbers, pick the winner, and move on. The easiest way to get better results? Keep it simple and keep iterating — that’s what works.