How to Write Subject Lines That Get Opened
You can write the most valuable email in the world…
But if your subject line flops, no one will ever read it.
The subject line is the gatekeeper of your email marketing success. It’s the first thing your audience sees, and it determines whether they’ll click open or delete.
In this post, we’ll break down:
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What makes a subject line irresistible
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Real-world formulas and examples that work
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Common mistakes to avoid
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Pro tips to boost your open rates — starting today
Let’s make sure your emails get noticed. 👀
Why Subject Lines Matter So Much
Your email subject line is like the headline of a blog post or ad. It’s there to grab attention and earn the click.
According to Mailchimp, average open rates range between 17%–28%, depending on your industry. But with the right subject line, you can blow past those numbers.
It’s not about tricking readers — it’s about sparking interest, offering value, or creating urgency.
✅ The Anatomy of a Great Subject Line
To write subject lines that get opened, you need to:
1. Spark Curiosity
Give just enough info to pique interest — but don’t give everything away.
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“You’re making this mistake right now…”
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“A weird tip I learned from a 7-year-old”
2. Be Clear About the Value
Tell people exactly what they’ll get if they open the email.
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“5 headline formulas that triple your traffic”
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“How to grow your list to 1,000 subscribers fast”
3. Create Urgency or Scarcity
Use deadlines or limited offers to encourage immediate action.
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“Ends tonight: Your last chance to join”
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“Only 3 spots left in the workshop”
4. Add Personalization
Include the subscriber’s name, location, or interests (if your ESP supports it).
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“Sarah, here’s your content calendar template.”
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“A special offer for freelancers in Chicago”
7 Proven Subject Line Formulas
Here are plug-and-play structures you can adapt to your brand and audience:
1. The “How To” Formula
“How to [Achieve X] Without [Frustrating Thing]”
Example: How to write high-converting emails without sounding salesy
2. The Question Hook
“Are you [struggling with X]?”
Example: Still fighting with your email open rates?
3. The Number List
“[#] Ways to [Achieve a Benefit]”
Example: 3 ways to grow your list using Instagram
4. The Quick Win
“Get [Result] in [Timeframe]”
Example: Double your opens in 5 minutes
5. The FOMO Trigger
“Don’t miss [Event/Offer] it’s almost gone”
Example: Only 6 hours left: Grab your free download
6. The Unexpected Twist
“What my dog taught me about email marketing”
Breaks pattern, sparks curiosity
7. The “Secret” Subject Line
“The subject line that boosted my opens by 42%”
Everyone loves a secret hack or insider info
❌ 5 Subject Line Mistakes to Avoid
Avoid these traps that kill your open rates:
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Being too vague: “Newsletter #57” (boring and unclear)
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Using clickbait: “You won’t believe this!” (annoying if it’s not true)
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Overusing CAPS or !!!: Looks spammy and gets filtered
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Including too many emojis: One can help. Three looks desperate.
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Ignoring your audience: What works for SaaS won’t work for parenting bloggers
A/B Testing Subject Lines (So You Know What Works)
Most email platforms like Mailchimp, ConvertKit, and ActiveCampaign allow subject line A/B testing.
Try testing:
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Curiosity vs. clarity
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Emoji vs. no emoji
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Short vs. long subject lines
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Personalization vs. generic
Tip: Test one variable at a time and give your list enough volume to reach significance.
Subject Line Best Practices (Quick Tips)
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Keep it under 50 characters (for mobile visibility)
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Use action words: boost, grab, build, discover
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Write 10 versions — then pick the strongest
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Think like your reader: what would you open in a crowded inbox?
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Match the tone of your brand (casual, professional, quirky, etc.)
10 High-Converting Subject Lines to Inspire You
Feel free to steal or remix:
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“Your free email swipe file is here ”
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“We made this just for you, Sarah.”
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“How I grew my list from 0 to 10k in 6 months”
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“You’re invited: A masterclass in email growth”
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“Only 3 spots left (and you’re on the list)”
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“A quick favor?”
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“New strategy I haven’t shared anywhere else.”
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“Want more clicks? Try this subject line hack”
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“Read this before you send your next email.”
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“ Today only: My best freebie yet”
Final Thoughts: Think Like a Human, Not a Marketer
If your subject line feels robotic, dull, or salesy, it won’t get opened.
The best subject lines feel like they’re from a real person, solving a real problem, not a brand pushing a product.
