Soooo here’s a truth bomb to start this blog…haha!
WE ALL IGNORE EMAILS
Whether it’s newsletters we forgot we signed up for or promos that straight up just piss you off, our inboxes are loaded with a lot of missed chances – for brands, for people, and for that one startup with potential but no idea how to get their message across.
But the cool thing is…we also actually open our inbox and READ EMAILS
So the question is what actually makes us open one email and ignore another?
In 2025, more than 375 billion emails will be sent and received each day – this means that standing out in a crowded inbox and reaching your audience is more challenging than ever. A great email subject line can make or break your campaign. It’s the first thing your audience sees, and it determines whether they’ll open your email or scroll right past it.
The truth is our brains are wired to respond to certain emotional triggers, even when we don’t consciously realize it. Smart marketers know this – and use it to create subject lines that light up parts of the brain tied to curiosity, fear of missing out (FOMO), urgency, and value.
By mastering the psychology of creating powerful subject lines, you can not only grab attention but also convey the value of the email’s content, improve open rates, engagement, and conversions.
So let’s talk about how to do this the right way, starting with the most foundational step: #1 – Keep It Short, Sweet, and Scroll-Proof.
Secret #1 – Keep It Short, Sweet, and Scroll-Proof
Your email subject line has maybe 2 seconds to earn a tap and that’s because nobody has time for a 12-word subject line that reads like a novel. Some marketers get nervous when we say “keep it short.” because for them ‘short’ means vague or underwhelming. But the truth is, short subject lines aren’t weak – they’re deliberate. They say only what matters, and leave everything else inside the email.
Think about it… how often do you open an email because the subject line said exactly what you were thinking, or made you curious, or simply felt like something a friend would send?
If you’ve ever seen subject lines like “Still interested?” or “This ends soon”, then you should know they don’t just work because they’re brief. They work because they sound like they came from someone who knows you. They play to human instincts: curiosity, urgency, belonging etc.
In fact, a recent research from Mailchimp shows that subject lines under 60 characters consistently perform better than longer ones – and this makes sense because on mobile devices (which is where most of us are) your subject line gets maybe 35-40 characters before it’s cut off. That’s it – that’s the window. Anything longer and you bury the good part of the subject line – the offer, the punch, the reason to care – at the end.
So even if your message is brilliant, your email won’t perform as well because your best line is likely the part no one ever sees. Which is why we recommend flipping the script and leading with the hook. Get in fast. Earn attention before the scroll takes it away.
Now, there are those times when you do have more to say… when the story can’t be told in five words. In these cases you can use a “longer” subject line – if you do it brilliantly. Longer subject lines can work when they create what psychologists call an “open loop”. Here’s how that works.
Let’s say you use a subject line like “We almost didn’t send this” or “She said something we didn’t expect.” – this creates a loophole – a question that demands an answer like “Almost didn’t send what?” and “What did she say?”, and the only way they’re getting the answer to their burning questions is to open the email.
So while we recommend you keep it short and sweet, your subject line – short or “long”, has to create an emotion. Whether it’s FOMO, curiosity, urgency or amusement… if you can’t name the emotion, your reader probably won’t feel it. And if they don’t feel it, they won’t open it. If it wouldn’t make you stop scrolling, it won’t stop them either.
Secret #2 – Personalize Beyond “Hey First Name”
So back in the day just throwing merge tags or personalization tags in your copy that changes something that looks like [firstname] or *|FNAME|* on your end to the recipients name was sooo cool – and it even got customers buzzing like “OMG, these guys know my name”.
Today? If your customers see an email where your only attempt at understanding them is just the fact that you can say their name? You’re getting blocked!
Now, at the same time, mentioning overly specific personal information, such as recent purchases or browsing history, without clear context or prior consent, might make recipients think you’re intrusive and do not respect their privacy. So the key lies in balancing personalization with respect for privacy.
So, if first-name personalization isn’t enough and TMI is too much, what is perfect? Behavioral personalization!
This method allows marketers create content based on a recipient’s actions and preferences. Which is why today, the best-performing subject lines don’t just say a person’s name – they react to context. So let’s say you own an eCommerce business. A “Still interested in those sneakers?” email subject line after cart abandonment, or a “Rainy weekend ahead? Our top indoor picks” email based on the weather in a customer’s location or zip code can feel helpful rather than pushy.
And even the timing of when that email hits your inbox makes a difference. Imagine getting a promo email for lunch deals at 3 AM. That’s a hard pass. But when a business sends stuff right around the time their audience usually checks their phone – say, mid-morning or right after work – it feels more natural.
Real brands are killing it with this kind of stuff. Take Spotify for example… they might send you a playlist with a subject line like “Your daily vibes are ready,” and the tracks are based on what you’ve been into lately. Or Airbnb might say “Spots to escape to this weekend” and it’s showing places within driving distance. It doesn’t feel like spam, it feels like something you might actually want.
So yeah, the era of just first-name drops in emails is kind of over. What smart marketers are doing now is using user actions to shape their message, sending it when it makes sense, and making the content feel like it was made for each reader? That’s where the magic still lives.
Secret #3 – Use Numbers and Lists
You ever scroll through your feed and your brain just… skips half the stuff? Same here. There’s just so much going on, you need something to grab you. Not in a “BUY THIS NOW” kind of way – but more like something that quietly says, “Hey, this’ll actually help.” That’s where numbers come in.
Numbers help your content feel clean, scannable, and digestible. Most people don’t click on “How to be healthier,” but they’ll jump on “7 Surprisingly Easy Ways to Feel Healthier by Friday.” It’s not a coincidence because our brains love structure – and numbers provide that.
When articles, social posts, and even emails are numbered, the reader gets a sense of what they’re in for. That little number at the front of a headline tells your brain, “Hey, this won’t be endless. You’ll be in and out with what you need.”
One interesting fact to drop here is the way our brains actually feel about certain types of numbers. Turns out, even and odd numbers make us feel differently. Studies in consumer psychology show that when we see “7 Ways to…” instead of “6 Ways to…”, that odd number catches us just enough to stand out. It’s like the content is subtly whispering, “I’m not just like everyone else.”
Now, we’re not saying you have to only use odd numbers or only even ones but being intentional about which you choose gives your message a little extra texture. If you want to feel familiar and trustworthy, go even. If you want to pop out a bit or seem more exclusive? Odd numbers might be your go-to. It’s one of those small things that has a bigger impact than you’d expect especially when paired with how you frame the whole message.
For example these two headlines: “5 Mistakes New Freelancers Make” vs. “5 Tricks to Land Clients as a New Freelancer.” One taps into anxiety and urgency (“Oh no, am I messing up?”) and the other taps into aspiration (“Ooh, I wanna learn the hacks”). Same number, totally different feeling. What you lead with – fear, curiosity, exclusivity, hope – directs how people emotionally react.
Your customer’s attention is a currency, and the way a headline frames what’s inside either gets them to click or scroll on by. If you’ve ever seen those timers that tick down on a product page or in an email: “Only 2 hours left!”, they make the recipient think “If I don’t act now, I’ll miss out forever.” This framing is what psychologists call it ‘loss aversion,’ where people hate missing out more than they love gaining something new.
Keep in mind however, that if you’re using a countdown to make something feel urgent, make sure the deadline actually ends and doesn’t just reset every time they visit the page.
Secret #4 – A/B Testing Your Subject Lines
Sooo… here’s the thing. Most people don’t know what’s working in their emails – they’re just guessing. And hoping. And maybe crossing fingers. You get the point. But that’s like throwing darts with your eyes closed. A/B testing fixes that. It’s how you stop guessing and start knowing.
Here’s how it works: you send two versions of something (subject line, CTA, vibe, whatever) to a slice of your list. Half get Version A, half get Version B. You wait. You see which one gets the most love – clicks, opens, replies, sales. Boom. Winner.
Now, what should you actually test? Start with subject lines – that’s your first impression. Test short vs. long, serious vs. casual, questions vs. statements. Then try different CTAs. Is “Book Now” better than “Let’s Talk”? You don’t know – yet. Even button colors can make a difference. Yes, really.
In fact, we test audience emotions for our clients here at Abervin Digital by deploying Emojis. Yep, the little guys. But here’s the thing: they don’t work everywhere. A fire emoji can work for a Gen Z fashion brand but it doesn’t always work well for a real estate agency. So the key thing is to know your crowd. Test your crowd – emojis vs no emojis. See what works and don’t assume they think emojis are as cute as you do.
Also, just because Version A got 12 more clicks doesn’t mean it “won.” You need enough people to actually matter. If you’ve only got 60 opens between both versions, you can’t make solid calls yet. Most platforms recommend testing with at least a few hundred people — or 20–30% of your list if it’s big. Let the test run till it completes so you have accurate data.
The mindset to have is even if the version you prefer doesn’t resonate with your audience, let it go. You’re not writing a novel, you’re sending emails. No one cares how clever you felt when you wrote it. The only thing that matters is what performs.
Tools like Klaviyo, Mailchimp, or ActiveCampaign, allow you A/B test and even auto-send the “winner” to the rest of your list.
So stop guessing, start testing so you can get better clicks, opens, conversions and cha-chings
Secret #5 – Segment Your Subject Lines by Audience Type
Most subject lines don’t do well because they try to speak to everyone. And when you talk to everyone, no one feels like you’re talking to them. That’s why smart marketers segment because blasting the same message to everyone on your list is a guaranteed way to water things down. This is where switching your subject line based on segments you create is important.
A new subscribers and a repeat buyer are not in the same frame of mind as it pertains to your business – and repeat buyers aren’t the same as people who ghosted you six months ago.
The mindset of your new subscribers is curious, maybe a little hesitant, and they don’t know you that well yet. Your goal here is not to wow them with urgency or serious discounts right off the bat. What they need is a first impression that counts. Something like “Welcome in – start here” or “Your 10% off is waiting” works because it’s low pressure. It says, “Hey, glad you’re here,” not “Buy something now.”
But once they’ve bought once or twice, the tone of your messaging has to shift. Now you’re dealing with repeat buyers – people who trust you enough to pull out their card. These folks don’t need long intros or hard sells. What they want is to feel like insiders. Like they’ve earned something. That’s where subject lines like “Back for round two?” or “We saved this for you” come in. You’re not trying to explain who you are anymore – you’re recognizing them. It’s subtle, but that switch from introduction to appreciation can make a big difference in whether or not your email gets opened.
Then there’s the third group: the quiet ones. Dormant users. These are people who subscribed, maybe bought something once, and then disappeared. With them, the goal isn’t to pitch – it’s to re-engage. To catch their eye and get them to remember why they signed up in the first place. You’re not shouting “50% OFF!” because they’re not listening to that anymore. Instead, try something like “Still into this?” or “We hit pause – ready to play?” It’s not desperate, it’s thoughtful.
The content’s the same. But how you frame it changes the outcome.
And yes, split testing helps here too. But don’t test random lines across your entire list. Test within each segment. Try urgency vs curiosity for your dormant users. Try playful vs direct for your returning customers. You’ll find patterns. And once you know what works? You scale that.
And that’s a wrap on 5 Proven Subject Line Secrets to Skyrocket Your Email ROI!
If you want people to actually open your emails in 2025 – not just let them rot in the inbox then you must use the stuff we talked about in this guide. Mix it up. Play with curiosity, emotion, clarity, weirdness. Try a question. Try an emoji. Try ditching the emoji. The point is: don’t sleepwalk through your subject lines… test, test, test.
Need expert help? Contact Abervin Digital at +1 307-271-5184 or visit Abervin Digital to check out our pricing and packages or learn how we can transform your email list.
