160+ Cold Email Subject Lines That Will Stand Out in Your Prospect’s Inbox

Every day, over 330 billion emails are being sent and received across the globe. 

Now that there’s 8 billion of us, this means at least 41 emails in a day for every single human being on the planet. 

Ridiculous, ain’t it?

Clearly, your prospect’s inbox is going to be cluttered. Nobody has the time to sit and sift through 1000s of emails in this world we’re living in, So, your prospects will simply scroll past your cold email if it can’t catch their attention the moment they open the inbox.

In that case, how do you ensure your little missive stands out among the 100s of other emails in your prospect’s inbox? 

Subject lines! Crafting great subject lines is the first step to writing the perfect cold email.

In fact, 47% of the recipients open emails based on the subject line alone.

So, subject lines have, inarguably, become the deciding factor when it comes to whether your emails will be read.

Subject lines help your email stand out, and set expectations in the prospect’s mind about what your cold email has in store for them.

So, here are the 8 different techniques that can help you write effective cold email subject lines throughout your email campaigns

8 Cold Email Subject Lines Techniques With Examples

Personalized Subject Lines

Why Does This Work?

We studied over 100k sales emails, and found that personalized email subject lines had an open rate of 35.69%, while emails with subject lines that weren’t personalized had only 16.67% open rate.

Why? Research indicates that personalization influences the decision-making process of customers. We interpret any information that relates to ourselves as meaningful. 

 We are attuned to hear our own names above everything else. So, in a sea of emails that boast discounts and click-bait messages, your simple subject line addressing them directly will be seen. 

How To Personalize Your Subject Lines?

Here are the different things to personalize your subject lines:

  1. Use prospect or company name
  2. Personal information – like geographic location, recent professional updates
  3. Their interests (sports, TV shows, films)

You can get all of the above info on LinkedIn or lead generation tools like LinkedIn Sales Navigator, Clearbit, or business intelligence software like Zoho Analytics.

Metadata’s SDR Manager, Ashley Dees, personalizes her subject lines based on something the prospects did outside of work. “Who wants to look at more stuff about work? No offense to our companies. We all love our companies and the work that we do, but make it fun. People like to have fun, make it about them,” she says.

An example: She found while researching one of her prospects that they wrote a short book. So, she crafted her subject line as, “metadata demo + {her name} // {name of her book}.”

By the way: Want to know how the best-performing reps are hitting 100% quota through cold emails and cold calls? Check out Klenty’s SDR X Factor interview series, where we spoke to 8 quota-crushing SDRs like Ashley, and curated their strategies for cold emailing and cold calling.

Subject Lines Asking Questions

Why Does This Work?

Humans are innately curious. When the subject line poses a question, the human brain develops a deep-seated urge to know the answer. Questions pique the prospect’s curiosity and urge them to open the email. 

Sam Holeman, top-performing rep from Momence, says this is why many public speakers begin their talks by asking a question. “This is like a basic lesson from college: You can start an essay by asking a question that makes you go up, that makes everybody pay attention,” he says.

How To Use Questions In Your Subject Lines?

Research the prospect’s goals, challenges, and pain points. Then pose questions about them. Their engagement on your subject line will affirm which pain points or challenges are their priorities. 

To know about their: 

Goals: – Glance over their official website, skim through their latest and related news articles to get a general idea about your prospect company’s current market position. Look at their company’s open roles. These job descriptions often reveal larger goals of a team or a function. 

Pain Points and Challenges: Go through any recent forum questions, Quora posts, LinkedIn comments to get an idea of problems your prospect might be facing.

Here are some question-based subject lines that Sam’s been using, which gets his cold emails opened:

  • “What is Momence? Here’s some basic information” (first email)
  • “Following up: When are you available?” (follow-up email)
  • “What is our next step, {First Name}?”  (breakup email)


Related: You can find additional information on the best personalized cold email subject lines at Cold Email Templates. This is the ultimate guidebook that comprises best-performing email templates and subject lines, tried and tested by industry experts.

Subject Lines With A Mutual Connection

Why Does This Work?

A mutual connection helps tone down the coldness of your subject line. When you mention that a mutual connection exists between you and your prospect, you are no longer strangers to them. Establishing a common ground puts the prospect at ease, making it easier for them to trust you.

Most importantly, mentioning the mutual connection in the subject line can help grab the prospect’s attention to your email in their shambolic inbox. In a way, this is a more refined type of personalization. Something familiar – something they know is bound to catch their eye.

How to Talk About Mutual Connections in Your Subject Line?

The mutual connection needn’t always be a person, like a friend or referral. It can be anything that establishes a common ground between you and your prospect. Like being part of the same LinkedIn group, sharing the same hobby, supporting the same sports team, having attended the same middle school, college, or university, or having been to the same event/conference.

But keep in mind that you don’t get too personal with their information. This subject line works well at any stage of your email outreach, whether it is your first email or a follow-up.

Short Cold Email Subject Lines

Why Does This Work?

Studies reveal that subject lines with 0-5 words have high open rates of 16% while those with around 21 words have an open rate of only 12%.

Another reason is that short subject lines perfectly fit the screens of mobile devices. Over 41% of working professionals read their emails on their mobile. And an average mobile screen can only fit 4-7 words max. Having a short subject line ensures your subject lines aren’t cut off midway due to lack of screen space.

Out of the 8 SDRs we spoke to for the SDR X Factor interview series, 5 reps said they prefer short subject lines for their cold email outreach. On average, their subject lines would only be between 2 and 6 words.

For instance, Ashley Dees likes to use the 2-word subject line “uh oh…” for her emails. Also, she keeps her subject lines lowercase to grab her prospect’s attention.

How To Shorten Your Subject Line?

Stick to subject lines with 2 to 5 words. If you’re feeling especially adventurous, A/B test 1- word subject lines. It has the highest open rates, according to the recent study we did at Klenty.

But avoid using overused subject lines to ensure the prospect doesn’t delete or mark your email as spam even without opening it.

“A few years ago, the cold email subject line “quick question” could often trick people into opening your spam out of curiosity. Now it is an instant sign of spam. Instant delete without opening,” says Andrew Cohen, CEO of Brainscape in one of his Twitter posts.

Short Subject Line Examples

  • Request to connect.
  • Gift for you
  • Are you ready?
  • Free {product} vouchers
  • 26 seconds (or less).
  • Just tried calling you.
  • Oh! I forgot to mention.
  • Next Step?
  • Time to Part Ways
  • Moving On.
  • It’s not you, it’s me.
  • Can’t decide?
  • Save money
  • Another chance?
  • Not a sale!
  • You busy {day}
  • There’s still time
  • Only {quantity} left
  • It’s official…
  • You won’t regret
  • Meet {product name}

Subject Lines That Create Urgency

Subject lines that create a sense of urgency and exclusivity can give you a 22% higher open rate, according to a report by Invesp.

Why Does This Work?

FOMO. Simple as that. The fear of missing out on something that may not be available in the future can make people act impulsively and make rash decisions. Using certain power words and phrases can make what you have to offer to seem scarce, rare, and special.

How To Create Urgency in Your Subject Line?

Find out if there are any events or situations that can bring about a sense of urgency and make the prospect want your product – a trigger event.

These events can be anything;

  • It can be an upcoming event,
  • A new regulation or law that’s going to come into effect,
  • A time-sensitive pain point or lowered pricing
  • The end of the quarter or year

Using these events, you can create a false sense of a deadline for your prospect and drive them to the body of your email.

Subject Lines With Value Proposition

You grab your prospect’s attention effortlessly when you promise value through your email subject line. Cold email subject lines about solving your prospect’s pain points or about the benefits of your product work for this reason. This is effective as long as your email copy delivers the value you promised through the email subject line.

SDR Manager at Klenty, Noel K, says, ‘Book More Meetings’, ‘Increase Your Revenue’ are some of the go-to subject lines that never fail to get opened. Even though these look like clickbait at first glance, they’re very related to our value proposition.”

How To Include Value Propositions in Your Subject Line?

Listing down and bucketing your prospects according to how they will use your product and how they can benefit from it should give you a clear picture. Then you can create a value prop subject line that suits each prospect accordingly.
Coming up with subject lines for cold emails that indicate what value/benefit you can offer is the key to baiting a prospect in. Subject lines about anything relevant to their field or a solution to their problems grab their attention and urge them to open your email.


Related: You can find additional information on the best personalized cold email subject lines at Klenty Cold Email Templates. This is the ultimate guidebook that comprises best-performing email templates and subject lines, tried and tested by industry experts.

Humorous Cold Email Subject Lines

Why Does This Work?

Prospects are people, after all, and will appreciate a joke or two from time to time. It takes them away from the busy day they are going through. So when you use a funny subject line, it puts your prospect at ease and makes your email stand out from all other monotonous and bland content in your inbox.

How To Add Humor in Your Subject Line?

Getting the right joke is tricky stuff and not everyone shares the same sense of humor as you. So, the jokes you tell your friends or family certainly cannot be used here without reading the room. The same goes for emojis in your sales email subject lines. Avoid them if you are unsure of your target audience’s reaction to them.

Learn a bit about your prospect to see what they like. For example, if your prospect is British or likes Brit humor, you can be innovative with some strong sarcasm and self-deprecating, dry humor. Or you could just quote any fancy line from Monty Python! ‘Tis but a scratch

However, remember that humor is subjective, especially in this day and age. So, choose your jokes, and make sure you know your audience. If done right and you get a laugh out of your prospect, you’d have earned major brownie points. If not, you might have to start drafting an apology letter.

Subject Lines with Social Proof 

Why Does This Work? 

Did you know that 63% of consumers want to hear company claims 3 to 5 times before they actually believe them? 

Obviously, you cannot keep talking about your own company so many times. This is where social proofs come in handy. Social proof, by the way, is a psychological phenomenon where people think that the action of others is the correct behavior for a given situation. 

Social proof in your cold email subject line is a great way to boost your email open rates.

How To Add Social Proof in Your Subject Line?

Embedding social proof in subject lines is easy but is often overlooked by most sales teams.  

Some of the common social proofs that you can add to your subject line include – 

  1. Testimonial
  2. Recent awards
  3. Influencer/celebrity mention
  4. Partnerships with major brands

When you add such proofs to your cold email subject line, your recipient will start picturing you more positively.


Writing cold email subject lines that are exceptional and attractive is not an easy task. Because different subject lines work for different prospects. The best way to find the most effective cold email subject lines is to perform A/B testing for subject lines.

Write different subject lines while you test, but make sure that your subject lines are honest, designed to help you engage with your prospects, provide clear information and value about what you offer.


How does personalization in subject lines help with open rates?

According to a recent study we did at Klenty, personalized subject lines are 35.9% more likely to be opened. Every personalized subject line conveys, ‘yes, this is for you and about you..’ to your prospects. They easily catch the prospect’s attention in a crowded inbox and hint at the pains you’ve taken to do the research.

How to find the best working subject line for a cold email?

The best way to find the most effective subject lines for your cold email campaign is to perform A/B testing for the subject lines. To find subject lines that get the highest open rate, test out different subject line texts that:
– Give clear information about the email
– Deliver value to the prospect
– Offers a solution to prospect’s pain points
– Creates FOMO in the prospect
– Build curiosity

Comments are closed.