If you’re sending cold messages and hoping for more replies, you’re in the right place. This guide is for marketers, founders, SDRs—basically, anyone who cares about getting better results from cold outreach without wasting time on guesswork. We’ll get into how to A/B test message variations using Colddm, what actually matters, and how to avoid spinning your wheels. No fluff, no B.S.—just the practical stuff.
Why Bother With A/B Testing Messages?
Sending the same message over and over and hoping for a bump in replies is wishful thinking. People are busy, inboxes are crowded, and small tweaks to your message can make a real difference. A/B testing—sending two or more versions of a message and seeing which one works better—takes out the guesswork.
But here’s what most guides won’t tell you: not every test is worth running. You don’t need to test every single word. Focus on what might actually move the needle (like your opener, call-to-action, or subject line).
Before You Start: What You Need
Let’s keep this simple. Here’s what you need to run a decent A/B test in Colddm:
- A Colddm account (obviously)
- A list of people to message (the more, the better, but at least 50–100 for each variation)
- Two or more message variations you want to compare
- Some idea of what you want to improve (e.g., reply rate, positive replies, meeting booked)
If you’re still building your list or haven’t used Colddm before, get that sorted first. Otherwise, you’ll just be testing on too few people to learn anything useful.
Step 1: Decide What to Test
Here’s where most people overthink things. Don’t test ten things at once. Pick one change per test.
Common things worth testing: - Subject line or first sentence (for cold email or LinkedIn InMail) - Personalization (generic vs. specific) - Length (short vs. long) - Call-to-action (“Interested?” vs. “Want to chat next week?”) - Tone (formal vs. casual)
Skip the temptation to test tiny tweaks like swapping one adjective for another. You want meaningful differences, or you’ll never see clear results.
Pro tip: If you’ve never tested before, start with the subject line or opening sentence. That’s where you’ll usually see the fastest impact.
Step 2: Write Your Variations
Write two (or maybe three) clear versions. Don’t mix in too many changes—if both your subject and call-to-action are different, you won’t know which one made the difference.
Example:
-
Version A:
“Quick question about your sales process” -
Version B:
“Thoughts on improving outbound results?”
Keep your variations as similar as possible except for the one thing you’re testing.
Step 3: Set Up Your Test in Colddm
Colddm makes this pretty straightforward, but here’s what actually matters:
- Create a new campaign (or duplicate an old one).
- When adding your message, look for the “A/B Test” or “Variants” feature. (If you can’t find it, check their help docs—features move around sometimes.)
- Paste in your two message versions.
- Make sure Colddm is set to randomly split your audience between the two versions. If you split it manually, you’ll introduce bias. Automation is your friend here.
- Double-check that each recipient will only get one version. You don’t want to spam anyone with both.
Don’t overcomplicate: Two variations is plenty. Three is fine if you have a big list. Anything more, and you’re just making more work for yourself.
Step 4: Launch and Wait (Seriously, Wait)
This is where patience comes in. Hit send and let the campaign run. Resist the urge to peek at the numbers after a handful of replies. You want a decent sample size before making any decisions.
How long should you wait? - For small lists (<200), give it at least a week. - For bigger lists, you might see trends sooner, but don’t call it until you have at least 50+ replies per version.
Ignore the urge to “pick a winner” after 10 responses. Randomness can fool you. Let the data come in.
Step 5: Measure Your Results
Colddm should show you reply rates for each version. If not, export the data and do the math yourself:
- Reply rate = (Number of replies ÷ Number of messages sent) x 100
Look for statistically significant differences—not just a 3% bump on a tiny list.
What’s a “real” result?
If Version A gets a 12% reply rate and Version B is at 8%, and you’ve sent at least 100 messages of each, that’s likely real. If it’s 12% vs. 11% on 30 messages? Don’t read too much into it.
Pro tip: Don’t just count any reply. You might want to track positive replies or meetings booked. Define what “good” means for you before you start.
Step 6: Learn and Iterate (Not Overthink)
If one version clearly outperformed, use it as your new “control” and try testing something else next time. If both performed about the same, try a more drastic change in your next test.
Don’t chase small, meaningless wins—focus on the big stuff. And don’t be afraid to rerun tests with bigger lists if you’re not sure.
What Works (and What Doesn’t)
Works: - Testing big changes (subject lines, tone, call-to-action) - Keeping tests simple and focused - Letting the test run long enough to get real data
Doesn’t Work: - Testing tiny tweaks (one synonym for another) - Drawing conclusions from small samples - Running too many variations at once
Ignore: - “Best practices” that don’t fit your audience. What works for SaaS might flop for healthcare. - Chasing every reply—focus on quality responses, not just volume.
Pro Tips for Better Results
- Personalize where it counts: If you have data on your recipients, use it in one of your variations.
- Always have a clear call-to-action: Vague asks get vague replies (or none at all).
- Don’t over-optimize: Sometimes, the difference between two average messages is just luck. Test, but don’t obsess.
Keep It Simple and Keep Going
A/B testing in Colddm isn’t rocket science, but it’s easy to get lost in the weeds. Focus on big changes, let your tests run, and don’t overcomplicate things. The best outreach campaigns get better by learning one clear thing at a time, not by fussing over every comma.
Test, learn, repeat—and don’t forget: sometimes simpler really is better.