⚡️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.
Hey, It’s Luis.
Hope your weekend was good. Mine involved a birthday party with the kids and the latest episode of Industry on Max — good show if you haven’t started it.
This week I want to share something I’ve been sitting on since August. A real A/B test. A real result. And a new subject line control that beat my old one by a meaningful margin.
THIS ISSUE INCLUDES
Reading time: About 7 minutes
My playbook: the swipe file.
“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. Here’s how I use it.
When something grabs my attention — a subject line, a campaign structure, a clever preview text — one of two things happens. Either I build a proof-of-concept campaign on the same day, ready to send to a customer segment by noon. Or I save it to the swipe file for the next time the situation calls for it.
A swipe file is simply a collection of what works: ads, headlines, emails, sales letters, design inspiration. You’re not copying — you’re channeling what’s already proven and applying it to your brand.
That’s the Copybeast method.
Three “Back in Stock” campaigns worth studying.
A Back in Stock campaign is typically sent to your main list one to three days after the automated restock alert goes to your waiting list. My recommendation: send it one day after the waiting list alert so your most loyal customers get first access.
Here are three examples from my swipe file — and what I’d do with each one.
Example 1 — Alex Mill
SUBJECT LINE + PREVIEW
Not sold out anymore – The cardigan with 5 stars
This one caught my attention immediately. “Not sold out anymore” is pure curiosity — it doesn’t tell you what the product is, just that it’s available again. Paired with “The cardigan with 5 stars,” you get social proof without saying a word about ratings or reviews. The reader does the math themselves.
I’m a regular Alex Mill subscriber. I recommend getting on their list.
TRY THIS 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 — designed to stop one specific type of reader cold. The subject line doesn’t say Back in Stock. It just says the name. If you know Off-White, you stop. If you don’t, you scroll past. That’s intentional. Nike isn’t trying to convert everyone — they’re trying to convert the right person fast.
RIP: Virgil Abloh.
TRY THIS ONE-TWO COMBO — best for vault items or cult products
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. The subject line does everything right — urgency, specificity, excitement. But it’s doing too much. “JUST RESTOCKED |” is a preamble that delays the hook.
If I were working with Hudson Grace, I’d split test their control against this:
TRY THIS 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.
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
Two weeks before this issue, a container of goods arrived at port. A few days later my client received it at the warehouse. I finally had my chance to test the Alex Mill subject line against my own control.
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.
Results
The Alex Mill-inspired subject line won with a 4.72% click rate.
My new control: 🇫🇷 Not Sold Out Anymore
Experiment #2
New hook confirmed. Time to test whether the Alex Mill preview could beat my existing one.
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.
Results
The full Alex Mill one-two combo won.
My new Back in Stock control:
Subject line: Not sold out anymore
Preview: The [item] with 5 stars
Key Takeaway
“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
The control is your enemy. Every campaign you send is an opportunity to find a new champion. Here’s the one-two combo that just became my new Back in Stock standard — make it yours and try to beat it:
Subject line: Not sold out anymore
Preview: The [item] with 5 stars
When you test it and find a new winner, let me know what happens.
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
Founder & Editor, Copybeast ⚡
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.
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