Subject lines are the gatekeepers of your emails.
You could write the best email ever, but if your subject line sucks? No one’s opening it.
Game over.
The subject line is like a movie trailer. It’s gotta be exciting enough to make people want to see the whole thing. If it’s boring, confusing, or looks like spam? You’re getting sent to the trash faster than you can say “unsubscribe.”
But what makes people actually open emails? What really works?
Let’s dive in.
Curiosity Is King
Humans are curious creatures. We can’t help it. If something grabs our attention and makes us think, “What’s that about?” we have to know more.
That’s why curiosity-based subject lines are killer.
Example:
“What I learned after sending 1000 emails”
Boom. You’re curious, right? You wanna know what I learned. So, you click.
Curiosity works because it leaves people hanging. And our brains hate not knowing things. It’s like when someone tells you, “I have something to tell you later.” You spend the whole day thinking about it, right?
That’s what you’re doing with a good subject line.
Keep It Short (And Sweet)
Short subject lines work better. Simple as that.
Why? People don’t have time to read a novel. Most people are checking their emails on their phone, so if your subject line is too long, it gets cut off. And no one’s clicking on a half-finished sentence.
Ideally, you want to keep it under 9 words or 60 characters.
Something punchy. Direct. Like this:
“Here’s what’s working now…”
Or:
“3 things you need today”
Short. To the point. Easy to read.
Personalization: It’s More Than Just a Name
Okay, here’s the thing. Personalization is a big deal, but it’s more than just using someone’s name in the subject line.
Sure, putting their name in there is nice, but what people really want is relevance. They want to feel like the email was written just for them.
For example:
“Daniel, here’s how to double your open rates”
That’s gonna grab attention because it’s not just any random email—it’s talking directly to you. You’re making it about their problems, their needs, and that makes it more compelling.
Alright, just a disclosure here, you shouldn’t start every email with their name. Just make sure you write it more often.
Don’t Be Spammy
This one’s huge. No one likes opening an email that feels like a scam or an infomercial.
So, avoid spammy words like “free,” “act now,” or “limited-time offer.” They scream “I’m trying to sell you something!” and people tune out instantly.
Instead, go for honesty. Be real with them. If you’ve got an offer, great—tell them why it’s good, not just that it exists.
(Here’s a link for you with a list of 45 Words & Phrases to Avoid in Email Subject Lines. Take a gander.)
Use Numbers
Numbers grab attention. If someone sees a number in a subject line, their brain says, “Ooh, this is gonna be specific and useful.”
For example:
“5 quick tips to boost your email list”
or:
“10 things you’re doing wrong in your emails”
Numbers work because they promise clear, actionable value. And people love knowing exactly what they’re gonna get before they even open the email.
Test. Then Test Again.
Here’s the deal: what works for one audience might not work for another.
The only way to know for sure what your audience responds to is to test. Try different subject lines. See what gets the most opens. Tweak things like tone, length, and curiosity.
Then do it again. And again. Testing isn’t just a one-and-done thing. It’s an ongoing process.
The Bottom Line
Subject lines are everything. They’re the difference between an email that gets read and an email that gets ignored.
Keep it short. Stir up curiosity. Make it personal. And always—always—avoid sounding spammy.
Get your subject line right, and you’ve already won half the battle.
Broken pencils are pointless,
Daniel Matievich