Latest / The Copywriting Podcast with Fexingo: Sales Letters, Headlines, and Persuasive Writing / How a Six-Word Subject Line Beat a Two-Page Letter
Transcript
- Lucas: There's a direct mail test from the 1970s that still haunts me. A two-page sales letter for a financial newsletter — beautifully written, every paragraph crafted to build desire — went up against a six-word subject line printed on a postcard. Luna: Six words on a postcard? That's not even a sales pitch, that's a tweet. Lucas: Exactly. And the postcard won by 18 percent. Let that sink in. Two pages of carefully reasoned argument, overcome by a single short sentence. Luna: What were the six words? Lucas: I'll get to them in a moment. But first, the context. This was a newsletter called 'The Money Letter' — pretty generic name — and the control package was a classic long-form letter with a lift note and a response card. The test piece was just a postcard with the subject line and an order form on the back. Luna: So the postcard had no body copy at all? Just the subject line? Lucas: That's right. No benefits, no testimonials, no guarantee. Just six words designed to make you want to learn more. The lesson is brutal: if you can't say something compelling in six words, you probably can't say it in six pages either. Luna: It reminds me of that old adage — 'I would have written a shorter letter, but I didn't have time.' The postcard forced the copywriter to find the single most urgent reason to respond. Lucas: And that's the part I want to drill into today. Because the six words weren't a generic headline like 'Money Secrets Revealed' or 'Beat Inflation Now.' They were specific and slightly mysterious. They were: 'What the Fed doesn't want you to know.' Luna: Oh, nice. That's not just a benefit — it's a secret. It implies knowledge asymmetry. Lucas: Exactly. 'What the Fed doesn't want you to know.' The word 'you' makes it personal. 'Doesn't want you to know' triggers curiosity — and a little bit of defiance. You're being invited into an exclusive club. Luna: And the two-page letter probably led with something like 'Dear Investor, Are you tired of inflation eating your savings?' — which is fine, but it's expected. Lucas: Exactly. The letter was good. Professional. But the postcard broke the pattern. It arrived in an envelope with a window, and the six words were visible through the window. So even before they opened the envelope, they knew what they were getting. Luna: Wait — the postcard was in an envelope? Lucas: Yes. It was a postcard mailed inside a standard #10 envelope with a clear window. So the recipient saw the six-word headline on the postcard through the envelope window. That's how it got opened. The headline did the work of both the outer envelope teaser and the entire sales pitch. Luna: So the envelope itself became part of the copy. That's smart. Lucas: Right. And the test wasn't just about length — it was about the psychology of how we process information. When you read a two-page letter, your brain goes into evaluation mode. You're looking for reasons to say no. But a six-word headline triggers a different response: 'I need to know what that means.' Luna: So the postcard bypassed the skeptical filter. It got people to say 'yes' to learning more, rather than 'no' to a commitment. Lucas: Precisely. And this is where the modern parallel gets interesting. Think about email subject lines today. You have maybe two seconds before someone decides to delete or open. The same principle applies. Luna: Are there any modern tests that replicate this finding? Lucas: Plenty. A well-known email marketing study — I think it was from Mailchimp a few years ago — found that subject lines between six and ten words had the highest open rates. But more importantly, subject lines that created curiosity — without being clickbaity — outperformed those that stated the benefit plainly. Luna: So 'What the Fed doesn't want you to know' would work just as well in an email as it did on a postcard. Lucas: Probably better, because email has even less attention to capture. But here's the thing — the test also tells us something about the reader's state of mind. When someone gets a long sales letter, they assume you're trying to sell them something. When they get a postcard with a cryptic headline, they assume you're sharing information. The framing is completely different. Luna: So the medium shapes the expectation. The postcard felt like a tip, not a pitch. Lucas: Exactly. And that's the deeper lesson: brevity isn't just about saving words. It's about changing the relationship between the writer and the reader. Short copy says 'I respect your time.' Long copy — even if it's good — can feel like 'I want your time.' Luna: That's a great way to put it. So how do you decide when to go short and when to go long? Because there are plenty of long-form sales letters that make millions. Lucas: Sure. Long copy works when the reader is already motivated — they're looking for a solution, they want details. But if you're trying to grab someone cold, like a postcard to a rented list, short and curious wins. The key is knowing where the reader is in the buying journey. Luna: So the six-word postcard was a top of funnel tool. It got them to opt in to the message. Lucas: Exactly. And then, presumably, the newsletter itself had longer copy to close the sale. The postcard wasn't the whole campaign — it was the door opener. Luna: Right. So the lesson isn't 'never write long copy.' It's 'start with the six words that make someone want to read the long copy.' Lucas: That's the entire episode in one sentence. If you can't find those six words, you're not ready to write the two-page letter. And I think that's what a lot of marketers miss. They start writing the body copy before they've nailed the headline. Luna: You know, speaking of things that work — I've been thinking about how this show itself is a kind of long-form pitch. And if these conversations have sparked something you've actually used in your own writing, that's the whole point. The show stays ad-free because listeners who find value in it sometimes choose to support it directly. There's a link at buy me a coffee dot com slash fexingo if that's something you'd like to do. No pressure, just a way to keep the typewriter keys clicking. Lucas: Yeah, and honestly, it's the reason we can spend an entire episode on a six-word subject line without a commercial break. So back to that postcard — one more detail I love. The postcard itself was printed on yellow stock. Bright yellow. So even the color screamed 'open me.' Luna: Oh, so it wasn't just the words — it was the visual contrast too. Lucas: Exactly. Yellow envelope, six words through the window. The entire package was designed to create a single moment of curiosity. And that's the takeaway: every element should serve that one moment. Luna: So what's the modern version of that? A brightly colored email? An emoji in the subject line? Lucas: Maybe. But I think the principle is more about stripping away everything that isn't the core curiosity hook. If you wrote a six-word subject line for your next email, what would it be? Could you make it so compelling that the entire email becomes optional? Luna: That's a good challenge. I think a lot of us could stand to ask that question before we hit send. Lucas: So try it this week. Take your next sales email and reduce it to six words. Then ask yourself: if I sent just this on a postcard, would anyone respond? If the answer is no, you're not ready to write the long copy yet. Luna: I'll do that. And I'll be curious to see how many of my own emails would pass that test. Lucas: I think the answer might surprise you. For me, it was humbling. Most of my subject lines were fine, but not 'six words on a yellow postcard' fine. And that's a higher bar than we usually set for ourselves. Luna: So the real takeaway: brevity is a discipline. It forces you to find the one thing that matters most. Lucas: And that one thing is often the only thing that gets read. So next time you write, start with six words. Make them count.