What Makes a Cold Email Subject Line Work? 30+ Examples to Learn From

TL;DR:

Cold emailing refers to sending an unsolicited message to potential leads. Cold email subject lines are the first thing people notice about your message. They are often the deciding factor in whether your emails get opened or ignored.

In this article, we break down the best practices for writing cold email subject lines and discuss what to avoid. We also provide 30+ email subject line examples to help you generate more leads and boost your email conversion rate.

In a world where people exchange 240 emails every minute, not trying to stand out in their inboxes won’t do you any favors. Oftentimes, whether your marketing outreach gets ignored or opened comes down to compelling cold email subject lines.

Luckily, there are lots of proven techniques that trigger curiosity and, as a result, turn prospects into engaged leads.

Let’s uncover what makes good and not the best subject lines for cold emails with specific examples. 

What is a cold email?

Cold emailing refers to sending an unsolicited message to someone you haven’t previously engaged with. This is your first opportunity to introduce prospects to your business or product and, if done properly, make a lasting impression. These types of emails are usually written with several goals in mind, such as getting companies to respond or take another desired action. To be more specific:

• Try your product or service for free.
• Join your newsletter.
• Visit your company’s landing page.
• Showcasing your products and services to potential buyers.
• Bringing in new leads.
• Promoting special events, webinars, or offers.
• Getting noticed by influencers, journalists, or the media.

But your first and foremost objective here is to start a new connection and form a bond, not just sell your products right away. Hence, cold emails are the first touchpoints that get people to move down the sales funnel. 

Initial outreach is what sets the tone. The way you position your product at this point can determine whether companies will perceive it as something valuable or another sales pitch.

A strong first impression starts with a relevant and catchy cold email subject line. Make no mistake; getting this wrong can make it or break it, and below are reasons why.

The tactical purpose of a cold email is to get the recipient to either respond to your message or take another desired action, for example, get a free trial of your product or service, subscribe to your newsletter, visit your landing page, etc. 

But the thing is… The intention you put into your cold email may not coincide with the choice of your recipient, who may get hundreds of similar emails. Yes, an average office worker receives more than 120 emails a day!

Let’s be honest: how often do you open messages from a stranger?

What is a subject line in an email?

An email subject line is a short text displayed in a recipient’s inbox that summarizes the content of your message. A compelling one grabs attention, sparks curiosity, and encourages the recipient to engage with it.

Why do cold email subject lines matter? They are essentially the first thing people notice about your message. This alone can determine whether your outreach to potential leads gets ignored in their inbox or is opened and acted upon. So the stakes are really high for companies or products.

First impression

You’ve probably heard about the power of first impressions. People are known to be quite biased and quick at making initial judgments. In fact, we need approximately a tenth of a second or up to 30 seconds to make a first impression about people, companies, or products. Not that much time, right? 

That’s not to say it’s bad; we face tons of decisions on a daily basis, making this mechanism crucial for efficiently navigating the world. But it’s the reality you need to face: you have only a few seconds to convey your products’ value once your outreach reaches prospects’ inboxes.

The so-called “Halo effect” is even more interesting. It’s actually a cognitive bias where an initial impression can distort our perception of everything that comes after.

So it’s safe to assume if your cold email subject line sounds irrelevant or generic, people won’t open it, let alone reply. 

But the good news? You’ve still got a great shot at making a positive impression about your products. 

Email open rates

Email open rates refer to how many of your emails were opened by each unique recipient. This metric indicates if your approach to companies is working and if your product messaging needs optimization. So, email open rates are crucial to track if you’re taking your marketing outreach campaign seriously. 

The industry standard is currently somewhere at 21.33%. But take these numbers with a grain of salt because many factors can impact the performance of your strategy. Specifically, your results might vary greatly depending on the number of prospects or companies you’re targeting, your personalization tactics, etc.

A well-written subject line directly impacts your cold email’s open rates. It’s the first thing prospects see and often the deciding factor on whether your email gets opened or ignored.

Spam

Sure, having your cold emails ignored is a hard pill to swallow, but landing in the spam folder is even worse. This might happen for 2 obvious reasons: people either report it, or it gets flagged by algorithms. 

There are lots of factors that might cause your marketing outreach to end up in this unfortunate situation. But since we’re talking about cold email subject lines, let’s focus on language that can trigger spam filters. Here are some examples of what’s best to avoid for your own sake:

• Don’t write subject lines in ALL CAPS
• Make subject lines personal
• Limit special characters (%, !!, ??)

Steer clear of spam trigger words: FREE, Act Now, Limited offer, You’re a winner, etc.

Don’t risk losing your potential leads’ credibility; follow these best practices to keep your cold email marketing strategy safe. 

Best practices for writing cold email subject lines 

We’ve gathered some of the best email marketing tips that can help position your product as the solution companies have been seeking.

Write short subject lines

Keeping your cold email subject lines concise is always a good idea. Not only does it prevent people from feeling overwhelmed, but it also ensures everything is visible on mobile devices. Getting this right is crucial, as the number of people checking emails on mobile devices keeps growing. Plus, this approach is more effective if you’re trying to reach busy executives at target companies.

A good rule of thumb is to stick to no more than 60 characters and keep it under 10 words. This keeps your cold email subject lines impactful and easy to read, improving their chances of being opened.

Make it personal

With so many offers these days, people get even pickier when it comes to the brands and products they choose. In fact, personalizing your content means meeting the expectations of 71% of customers. Quite a number, right?

Our love for personalized content comes down to two factors: the need for control and information overload. Simply put, personalization frees us from feeling bogged down, sifting through irrelevant content, and making extra decisions. Such content feels aligned with our needs, instilling a sense of control and providing a manageable framework for engagement.

The most common personalization practice is probably mentioning customers’ names. But why limit your efforts to this only? 

Take a moment and approach your research seriously. Consider using LinkedIn to find out more about your prospects, their recent activities, interests, etc. Mention in your cold email subject line something very specific about their book, article, or recent blog posts.

Referencing specific details is more likely to generate qualified leads than generic product pitches. But remember to keep your outreach genuine, as people easily detect generated robotic messages.

Find a connection

People often open cold emails because they feel a connection. We’re more likely to trust and pay attention to those we feel we have something in common with.

Even if the email is from a stranger, we’re more likely to read it if we think there’s a shared bond. It gives the feeling of already knowing the person. You can create this connection by mentioning a mutual contact, school, or event (e.g., a marketing conference).

Just remember, always be honest about any connection. Don’t make up details or lie about who you know. Find something real in common with the person and use it in your cold email subject line.

Pique curiosity

It’s important to align your cold email subject lines with your message. Also, write them in such a way to ensure they resonate with your prospect’s needs. Remember that the goal at this point is to spark enough interest in your product that potential leads can’t resist opening the email. 

Don’t make the mistake of giving it all away to quickly. Make sure your subject line offers just a glimpse of what’s inside, enough to get people or companies interested. Below are a few effective marketing tactics to help you grab attention:

• Address pain points: Mention a problem or a challenge your prospect is facing in your cold email subject line. This makes your message feel directly relevant and gives them a reason to open it.
• Tease a solution: Mention a tool, strategy, or method that’s worked for other companies, giving a hint about how you can help.

• Share industry insights: Reference a recent trend or key information that’s relevant to their business or product. This shows you’re up-to-date and positions your email as something worth reading.
• Mention a competitor’s success: Talk about a competitor’s recent achievement and the way they did it. This can trigger curiosity and suggest that the prospect could achieve similar results.

By taking into account these strategies, you can write subject lines that generate interest from potential leads. And remember that the key in email marketing is to be relevant and create curiosity without giving away everything up front.

Use trigger words

Including trigger words increases the odds of your emails getting higher response rates. And no one is talking about those “free iPhone” spam trigger words that go straight into the junk folder. 

Power words (or trigger words) are emotionally colored expressions that tap into emotions, provoking a recipient’s reaction. They help make opening your emails harder to resist by appealing to all kinds of emotions, such as curiosity, urgency, etc. 

But why is that so? We all like to think of ourselves as logical beings, but we simply can’t ignore the truth that we’re also emotional creatures. Antonio Damasio, a professor of psychology, claims that emotions influence our decision-making process just as much as, if not more than, logic does. 

With this knowledge in mind, let’s explore some examples of words you can use when crafting your cold email subject lines:

• Secret: people love feeling like they’re getting insider info. Just make sure you deliver something juicy.
• Easy: everyone’s favorite word. Who doesn’t want a shortcut? Promises minimal effort and maximum results.
• Everyone: the FOMO generator! Taps into our deep fear of missing out. Suggests, “If everyone’s doing it, it must be good!”
• Proven: instant credibility booster! Shows your stuff actually works. But only use it if you’ve got real evidence to back it up.

Now, these little marketing tricks are at your disposal, take full advantage to make your cold email subject lines irresistible to open.

Use numbers 

Statistical data and percentages are incredibly persuasive when it comes to email marketing. This is because of ‘majority influence’ — the psychological tendency to follow the crowd. When people see numerical proof, whether it’s a success rate or an industry benchmark, they feel reassured in their decision-making.

Experiment

Unfortunately, there’s no secret formula to ensure your subject lines for cold emails always get the results you want. There’s also no one-size-fits-all approach, so testing and optimizing is your best bet when it comes to marketing. This gives you plenty of room to experiment, making you better at discerning quality messages that resonate with your audience. 

When playing with subject lines, many people rely on guesswork. A/B testing offers a smarter solution. By systematically comparing different versions, you can uncover exactly what makes your audience click, turning random experiments into precise, data-driven improvements.

Key tips for effective email marketing campaigns:

• Test one element at a time, such as word choice, length, or tone
• Create meaningful variations that can provide statistically significant insights
• Ensure your sample size is large enough to draw reliable conclusions

Luckily, today’s cold email software has made A/B testing incredibly accessible.

Outreach platforms now offer built-in features that can automatically split-test your subject lines and track performance.

Cold email subject line examples

 Wondering what to put in the subject line of an email? We’ve compiled a list of 30+ attention-grabbing email subject line ideas that might add a touch of inspiration to your marketing routine. 

Cold email subject line examples for sales

A clear value proposition and urgency are key when sales emails are in question. Focus on emphasizing cost savings and competitive insights.

• How [mutual contact/school/event] led me to you
• From [shared experience/place/background]
• Thoughts on your AI ethics piece
• Your TechCrunch article on AI changed my perspective
• [Name], your method challenges conventional wisdom

Cold email subject line examples for industry insights

Stats, research, and insider information are what people truly love. Make them feel like they’re opening a secret box filled with SaaS trends, business growth insights, and more.

• Cybersecurity’s uncomfortable truth for [company/industry]
• Why outsiders rewrite the rulebook in [industry]
• The hard truth about [industry] growth you’re missing
• The strategy 88% of [industry] ignore
• What your work leaves unsaid about [topic]
• The 7 silent killers of [industry] growth
• Machine learning’s invisible transformation in [industry]
• [Industry] growth pitfalls you’re not seeing
• The hard truth: 89% of startups miss this
• When imposter syndrome meets real innovation
• Why playing it safe in [industry] is the riskiest move
• Breaking the unwritten rules of [Industry]

Just remember, these examples are a starting point. Be sure to personalize them to reflect your unique style and message. 

And if writing still feels like a challenge, an AI email writer can assist you in no time. It provides customizable tones, grammar checks, and even supports translations into 36 languages.

Mistakes to avoid when writing cold email subject lines 

Just like we’ve discovered what works in email campaigns, let’s uncover some practices that prevent your product from reaching potential leads at target companies. 

Don’t ask without giving

Doing something for a complete stranger with no context or any real benefit to it? This approach rarely generates quality leads. 

As we’ve already said, you should clearly communicate why your product matters to your prospects.

Examples:

• Sign up for our webinar
• Looking for feedback on my product
• Can we schedule a demo?

Don’t make false claims

Play it safe by complying with the CAN-SPAM Act. It says that a subject line for emails should accurately describe the email’s content.

Other questionable tactics, such as using misleading prefixes or clickbait subject lines, won’t do your product any favors. They typically trigger spam filters, and even if they don’t, people still tend to delete or ignore them. 

What’s even worse, these actions, more often than not, lead to spam complaints. This eventually damages your sender’s reputation, making it harder for your emails to reach company inboxes in the future.

Examples:

• URGENT: Response needed immediately
• You won’t believe these results
• Re: Our previous conversation

Don’t sound too formal or pushy

Keep your cold email subject lines relaxed and natural. Don’t make them sound overly formal or pushy, and avoid jargon. 

Prospective leads don’t want to see another sales email in their inbox, especially from someone unfamiliar. Write in a friendly, conversational tone while still being polite in your outreach.

Examples:

• FLASH SALE – 50% OFF TODAY ONLY
• Revolutionary SaaS implementation for enterprise-level optimization

Don’t write vague subject lines

In a world of information overload, refrain from requiring your potential leads to do any extra guesswork. Generic subject lines like “Quick question” may not be worth the effort for many. They, obviously, can sometimes feel intriguing, but not for those with overly busy schedules. 

Vague subject lines don’t provide much reason or incentive for people to engage with your outreach. Offering a glance into what companies can get by opening your email is way more productive.

Examples:

• Just wanted to share
• Something you might like
• Interesting opportunity

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How to make an eye-catching subject line (having considered all of the above)

Here’s your final checklist for the irresistible cold email subject line:

✔️ Start with the recipient’s name. This helps personalize your email and makes it seem like you’re addressing them specifically. 74% of marketers who’ve tried this approach admitted a sufficient increase in customer engagement, and even more — they claim an average 20% rise in sales when using targeted personalization.

✔️ Keep it short and sweet. The subject line should be no more than 60 characters to be easily visible on mobile devices. It’s vital to stick to this rule as the number of emails opened on mobile devices has increased dramatically in recent years. Imagine how many of your subscribers will stumble over a too-long subject line they can’t read in full. Well, a too-short, one-word subject line won’t do either, as it can hardly get your message across to your subscriber. 

✔️ Don’t use Caps Lock as it may seem that you shout. Really, CAPITALIZED SUBJECT LINES create an impression that you’re screaming in a childish demand for attention. Furthermore, they trigger spam filters, increasing the chances for your email to be trashed.

✔️ Use statistical data. It works. The fact is that most people tend to perceive statistics as objective and unbiased information they can trust. So, never miss the chance to use stats in your subject lines as a quantifiable and highly persuasive accent to your message.

✔️ Avoid exclamation marks as not all people can accept the too enthusiastic a-la direct marketing style. Subject lines are best to be ended with a neat full stop. Surprisingly, a simple stop mark can boost your open rates up to 20%, recent stats reveal. Questions also perform well. It’s also popular to end subject lines with no punctuation at all.

✔️ A/B test your subject lines. You may craft your subject lines alone while sipping coffee, or you can involve your team to brainstorm and find the best variants. However, we don’t recommend starting a large-scale email outreach campaign without prior testing it. You’ll be surprised how elusive the marketers’ opinions can be compared to the real-life user. 

Wrapping up

Subject lines matter, especially in cold emails. When sending a message to a potential customer, the subject line is your opportunity to intrigue them and get them to open the email. If your subject line is boring or irrelevant, there’s a good chance your email will end up in the trash bin. 

But with our highly responsive cold email subject line examples, you’ll be able to create attention-grabbing headings that will increase your open and response rates. 

And when it comes to conducting a thorough email address search to create a targeted prospecting list, Snov.io is the best solution.

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