⚡️The Subject Line That Beat My Control by 4.72%
A real A/B test, three "Back in Stock" campaigns, and a new one-two combo you can deploy this week.
I almost didn’t run this test. I thought my control was unbeatable.
I’d been sending the same Back in Stock subject line for two years. It converted. My clients trusted it. And then I opened my inbox one morning, saw an Alex Mill email, and felt something shift.
That feeling is the signal. When a subject line stops you cold, you put it in the swipe file and you test it as fast as you can.
“When do you add to your swipe file? The answer is whenever you see something that grabs your attention!” –Jim Edwards, Copywriting Secrets
I’ve kept a swipe file for two decades. It’s helped me generate millions for my clients, not because I’m copying, but because I’m channeling what’s already proven and applying it to a new context.
That’s the Copybeast method. And this week I’m going to show you exactly how it works, from inbox to test to a new control.
Three “Back in Stock” campaigns worth studying.
A Back in Stock campaign goes out after the automated restock alert hits your waitlist. The waitlist takes care of itself, that’s the flow. The campaign is a different move. You’re going to your segments: your buyers, your browsers, your lapsed customers. That’s where the volume is. That’s where the revenue is. Here’s what three premium brands did and what I’d do differently with each one.
Example 1: Alex Mill
SUBJECT LINE + PREVIEW
Not sold out anymore - The cardigan with 5 stars
This subject line stopped me immediately. “Not sold out anymore” is pure curiosity — it doesn’t tell you what the product is, just that it’s available again. The preview closes it: “The cardigan with 5 stars.” No mention of ratings. No mention of reviews. The reader does the math themselves, and that math feels like discovery.
That gap between the subject line and the preview is doing real work. The subject line opens a loop. The preview closes it with social proof. Together they earn the open without overselling it.
My one-two combo:
Subject line: Not sold out anymore
Preview: The [item] with 5 stars
Example 2: Nike x Off-White
SUBJECT LINE + PREVIEW
Nike c/o Off-White™️ - “BACK IN STOCK”
This is a flag, not a headline. The subject line doesn’t describe the product; it just says the name. If you know Off-White, you stop. If you don’t, you scroll past. Nike isn’t trying to convert everyone. They’re trying to convert the right person fast.
RIP: Virgil Abloh.
My one-two combo:
Subject line: [Item Name]
Preview: “Back in Stock”
Example 3: Hudson Grace
SUBJECT LINE + PREVIEW
JUST RESTOCKED | Berry Bowls are back! - Wash, serve & store in style with a vintage-inspired favorite
Hudson Grace is a boutique home décor brand out of San Francisco with great taste, great products, and a subject line working against itself. “JUST RESTOCKED |” is a preamble, it delays the hook by four words before the real subject line even begins. The reader’s eye has to clear it before landing on the product, which is actually interesting.
Berry Bowls are back. That’s specific, visual, and seasonal. It deserves to lead.
This is the buried lead. And if you were my client, I’d kill the preamble the same day I read it. Your subject line has one job: earn the open. Every word that isn’t doing that job is a word working against you.
My one-two combo, less is more:
Subject line: 🍓🫐 Berry Bowls are back!
Preview: Wash, serve & store in style with a vintage-inspired favorite
Let the product name lead. Strip the preamble. The emojis do the visual work that “JUST RESTOCKED |” was trying to do, but faster.
On the average, five times as many people read the headlines as read the body copy. It follows that unless your headline sells your product, you have wasted 90 per cent of your money.” –David Ogilvy, Ogilvy on Advertising
The pattern across all three.
The subject lines that work fastest open a loop the preview closes. Curiosity in the subject. Proof or specificity in the preview. The reader connects the two in a split second and that connection is what earns the open. Every word that delays that connection costs you.
Two weeks after I saved that Alex Mill email, a container of goods arrived at port. A few days later my client received it at the warehouse. I finally had my chance.
Objective: find the one-two combo with the highest click rate.
Experiment 1: can “Not sold out anymore” beat my control?
Variation A (Control)
Subject line: 🇫🇷 These Favorites are Back in Stock
Preview: Back, but not for long.
Variation B (Champion)
Subject line: 🇫🇷 Not Sold Out Anymore
Preview: Back, but not for long.
The Alex Mill-inspired subject line won with a 4.72% click rate. New hook confirmed.
Experiment 2: can the Alex Mill preview beat mine?
Variation A (Champion)
Subject line: 🇫🇷 Not Sold Out Anymore
Preview: The [item] with 5 stars
Variation B (Control)
Subject line: 🇫🇷 Not Sold Out Anymore
Preview: Back, but not for long.
Variation A won with a 3.39% click rate — a 40% lift over the control. Win probability: 86.59%. The full Alex Mill one-two combo is the new Back in Stock control.
Your battle plan.
Start a swipe file today.
One folder. Subject lines and previews only. Every time something in your inbox stops you, save it. You’re not collecting ads. You’re building a library of proven desire.
Find your buried lead.
Pull your last five Back in Stock subject lines and look for preamble. “JUST RESTOCKED |”, “You asked, we listened:”, “It’s back!” Anything that delays the product name is a split test waiting to happen. If you were my client, I’d want that list on my desk before your next send.
Run the one-two combo.
Take the Alex Mill formula and test it against your current control: Not sold out anymore as the subject, The [item] with 5 stars as the preview. One test. Real data. See what your list tells you.
Back what wins and keep testing.
When you find a new champion, don’t retire it. Run it until it stops converting. More of what’s working before you touch anything else. The control is your enemy. Every send is a chance to find a better one.
“There is nothing more exhilarating for a copywriter or marketer than getting a new control—a campaign that sets a new standard of performance, converts first-time buyers into second-time buyers or renewals, pays out by whatever criteria is necessary, brings customers back as multibuyers over and over, and, simply put, beats the pants off the previous control.” –Brian Kurtz, OVERDELIVER
Two years I ran the same subject line. One morning, my inbox changed that.
My New Back in Stock Control
Subject line: Not sold out anymore
Preview: The [item] with 5 stars
If you were my client, I’d tell you the same thing I tell every brand when they find a new control: back it until it stops winning, then come find the next one.
Follow a premium brand with emails worth studying? Drop it in the comments. If I feature it in a future issue, I’ll give you the credit.
Talk soon,
Luis Lozano
⚡️Copybeast
”Helping e-commerce brands build marketing assets that compound revenue.”
P.S. The three swipe file campaigns — Alex Mill, Nike x Off-White, and Hudson Grace — are waiting for you below. Download them and add them to your collection.
