Latest / The Copywriting Podcast with Fexingo: Sales Letters, Headlines, and Persuasive Writing / How a Two-Word Subject Line Doubled Open Rates
Transcript
- Lucas: Okay, so last week I was digging through the results of a pretty big B2B email launch — a $2 million SaaS product rollout — and one number just jumped off the page. Luna: What kind of number? Lucas: A subject line that doubled the open rate of every other variant they tested. And it wasn't clever. It wasn't a pun. It wasn't personalized with their first name or a dynamic field. Luna: So what was it? Lucas: Two words. 'Quick question.' Luna: That's it? No company name, no urgency, no benefit? Lucas: Nothing. Just 'Quick question' — all lowercase by the way, which I think actually helped. The control subject lines were things like 'Your trial ends in 3 days' and 'See what you're missing' and 'Our new feature is live' — all standard SaaS fare. The 'Quick question' variant hit a 67 percent open rate. The median across all variants was about 31 percent. Luna: That's a massive gap. But doesn't that feel a bit... manipulative? Like, you open it and it's not really a quick question, it's a sales pitch. Lucas: That's exactly the tension. And I want to dig into that, because I think there's a real craft question here: when does a curiosity gap become a bait and switch? But first, let's talk about why it works on a psychological level. Luna: Alright, break it down. Lucas: There's a concept called the curiosity gap — the idea that when we sense missing information, our brain creates a mild discomfort that we want to resolve. The best subject lines don't answer a question, they open one. 'Quick question' doesn't tell you what the question is. Your brain immediately starts speculating: Is it about my account? Did something go wrong? Do they need feedback? That gap pulls you into the email. Luna: But it also relies on social pressure. If someone says 'Quick question' to you in person, you'd feel rude not responding. It's a social obligation trigger. Lucas: Right. And that's the other layer. It mimics the language of a colleague or a peer, not a marketer. It's conversational. It doesn't scream 'I am a broadcast message sent to 50,000 people.' It sounds like a one-to-one message. That's incredibly hard to pull off in email. Luna: So the copywriting lesson here is: sound like a person, not a company. But we also need to talk about the follow-through. What happened when people opened that email? Lucas: The body copy opened with, and I'm paraphrasing, 'I know you're busy, so I'll keep this brief — do you have 2 minutes to answer one question about your experience with?' And then there was a simple button: 'Sure, take the survey.' That email converted at a 14 percent click-through rate. Not bad. Luna: So the subject line set the expectation of a quick interaction, and the body respected that. That's key. If they'd opened with a 500-word sales letter, the trust would have been broken immediately. Lucas: Exactly. The subject line and the body have to be congruent. The biggest mistake people make with curiosity-gap subject lines is they promise one thing and deliver another. That kills not just that email's response but your future deliverability and sender reputation. Luna: Speaking of reputation — let's talk about frequency. If you send 'Quick question' every week, it stops working. The novelty wears off. So how do you sustain a tactic like this? Lucas: You don't. This is a once-or-twice-a-year move, not a template. The company that ran this test told me they reserve this subject line pattern for milestone moments — trial expirations, major feature launches, customer feedback requests. If you overuse it, you train your audience to ignore it. Luna: It reminds me of something David Ogilvy said: 'You cannot bore people into buying your product.' The 'Quick question' subject line isn't boring, but it's also not trying to be entertaining. It's just respectful of the reader's time. Lucas: That's a great connection. Ogilvy's headlines for Rolls-Royce — 'At 60 miles an hour the loudest noise in this new Rolls-Royce comes from the electric clock' — that's also a curiosity gap. You read that and you think, how is that possible? You have to read the body copy to find out. Same mechanic, different medium. Luna: So the principle is: create a gap, then fill it honestly. What about the opposite approach? Some brands get great results with very long subject lines — like 80 characters or more. Lucas: Yeah, there's research from Mailchimp and others that shows longer subject lines can outperform shorter ones in certain contexts. But I think the key variable isn't length, it's relevance. A long subject line that clearly states a benefit can work if the audience is already highly targeted. 'Quick question' works because it's short and universal. It's a different play. Luna: I want to talk about the downside. I've seen people try this in B2C and it backfires. Like, if you get an email from a clothing brand saying 'Quick question,' you know it's not a real question. It feels fake. Lucas: That's a really good point. I think the tactic works best when the relationship already has some weight — like a SaaS trial where there's an actual account, an actual person. In B2C, the context is usually weaker. If you're a retailer and you send 'Quick question,' people just think it's spam. Luna: So context and relationship matter. Let's talk about another example I found. A newsletter writer I follow — I won't name them because I don't want to make this about one person — but they tested 'Hey,' as a subject line. Just that. And it outperformed '5 tips for better sleep' by 40 percent. Lucas: That's fascinating. Because 'Hey,' is even less informative than 'Quick question.' It's purely a social opening. But it works because it's the way a friend would start an email. You're essentially saying, 'I'm writing to you personally.' And for a newsletter from a trusted creator, that can feel authentic. Luna: But again, you can't do that every time. It's a spice, not the main dish. Lucas: Exactly. So let's pull back and ask: what's the general principle here? I think it's that the best subject lines don't try to sell — they try to start a conversation. They're the first turn in a dialogue, not a broadcast announcement. Luna: And the second principle is: brevity forces clarity. When you have only two or three words, you can't hide behind jargon or fluff. You have to get to the point. Lucas: Right. But brevity alone isn't enough. It has to be specific to the reader's situation. 'Quick question' works because it implies the question is about them. 'Update' doesn't. 'Your invoice' might. It's about choosing words that carry social or contextual weight. Luna: Let's talk about A/B testing. A lot of people hear about a tactic like this and just copy it without testing. What's the best way to test subject lines? Lucas: The gold standard is to test one variable at a time — ideally on a small segment of your list first. And you need a big enough sample. For statistical significance, you generally want at least 1,000 opens per variant. But more important than the math is the learning: you're not testing to find the 'best' subject line forever. You're testing to understand what your specific audience responds to. Luna: And you have to track the full funnel, not just open rate. A subject line that drives opens but kills clicks or leads to unsubscribes is a net negative. Lucas: Absolutely. In the 'Quick question' campaign, the click-through rate was strong, but they also tracked survey completion rate and downstream conversion. The people who opened that email were more likely to complete the survey and eventually upgrade — so it wasn't just a vanity metric. Luna: So what's the takeaway for our listeners? If they're writing a subject line tomorrow, what should they do differently? Lucas: I'd say: before you write the subject line, write down what your reader is thinking right now. Are they busy? Distracted? Skeptical? Then ask: what's the one thing I could say that would feel like a respectful interruption rather than an intrusion? Sometimes that's a question. Sometimes it's a specific benefit. But it's almost never a generic marketing phrase. Luna: I think that's a good place to pause and mention something. If this kind of practical breakdown is useful to you — and you want to help us keep these episodes free and without ads — there's a simple way to support the show. Lucas: Yeah. We don't run sponsor spots or track you for ad targeting. That's a deliberate choice. If you'd like to chip in, buy me a coffee dot com slash fexingo is where a handful of listeners help fund these conversations. Even a couple of dollars a month makes a difference. Luna: It's a small ask, and it goes straight into production time and research. So if today's episode was worth a coffee, that's the link. And thanks to everyone who already does. Lucas: Okay, back to subject lines. I want to give one more quick example from the same campaign. They also tested 'A question about your account' — six words — and it underperformed 'Quick question' by about 20 percent. That tells me that adding context actually hurt, because it made the email feel more transactional and less conversational. Luna: So specificity can backfire if it makes the email sound like a system notification rather than a human message. Lucas: Exactly. The lesson is: the closer your subject line sounds to a real person starting a real conversation, the better it tends to perform — provided you follow through with authentic content. Luna: That's a good note to end on. Next time we should talk about email body copy — how to keep that conversational tone once they've opened. Lucas: Absolutely. And maybe test a few subject lines live on our own list. Luna: I'd be curious to see what happens. Lucas: Alright, that's it for this episode. Thanks for listening.