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8 cold email subject lines for high open rates

Nishit Asnani

6 minutes

Cold emails generate leads. They generate interest and buying intent. Cold emails are the foundation of the outbound lead-generation process of startups and big companies alike.

We’ve tried cold emails ourselves, and have found some interesting insights.

In this post, I share some of our insights about cold email subject lines that work. Some of them are counterintuitive, others support the advice of cold email gurus.

A good subject line is not enough

Email open rates depend on many factors. The subject line is one of the most important but is not the only factor.

Your email may not be opened if:

  1. It’s not delivered to the primary inbox of the prospect (people don’t open promotions or updates as much)
  2. It is delivered to the spam folder
  3. It is delivered at the wrong time (by the time the prospect opens her inbox, it’s already at the bottom of the pile)
  4. It has a poor pre-header or lead-in (the text that you see right after the subject line)
  5. You use your company name as the sender (people open emails from company names only when they recognize the brand, your own name is almost always better)

If your company email domain’s health is poor or your emails regularly land in promotions or spam, those would be bigger issues to fix than your subject lines.

Your subject lines don’t matter if the prospect doesn’t even see your email pop up in their inbox.

So, fix that first. If you've already gotten that fixed, let's dive into what makes a good subject line.

Why subject lines are not one size fits all

“32 sales email subject lines that work”

“20 cold email subject lines that produce results”

Most articles on this topic have headlines like the ones above (this one is no different).

As you might have seen, the article that you are reading right now is not the only resource on subject lines.

While there are plenty of subject line lists out there, it’s important to keep in mind that copying subject lines that have worked for others won’t work for you.

Yes, this is another article with a list, but your focus should be on the insights gained from the subject lines that worked, and not on copying them right away.

Here’s why:

  • Getting your prospect to open an email and take action is about understanding their psychology. A subject line may work for one persona (eg., CEO) but might fall flat for another (eg., VP of Sales).
  • Subject lines work when they stand out. Corporate inboxes are inundated with marketing and sales emails, and no executive has a reason to open an email from an unknown source unless it stands out from the crowd.
    And what stands out changes over time. A subject line that was a hit 6 months ago would have likely become overused and stale by now. Especially a subject line that’s in a public blog post.
  • The subject line shouldn’t seem like clickbait. If your subject line and email content have absolutely no relation to each other, the prospect sees through your intentions and it’s not a good look. Thus, using subject lines lifted straight from a list may not help.
    How would you feel if you opened an email and got the impression that the email sender was manipulating you into opening their email? The end goal is getting a reply, and an unrelated but catchy subject line doesn’t do you any good.
  • You can always craft cooler subject lines for your product or service than a generic list builder can. So it’s important to adapt, experiment and iterate.

This post talks about subject lines that have worked for us. What’s important is to take our learnings and insights, and adapt them to your use case.

Now, let’s get into it!

8 Subject Lines and Insights

Keeping it short?

Will Allred from Lavender recommends keeping subject lines to 2-3 words max. We decided to test it out.

Guess which subject line did better?

  1. “[use case] for video calls”
  2. “[use case]”

Come on, take a guess.

If you went for (b), you are right. Will was right, and we’ve seen this pattern repeated across different subject line experiments. A shorter subject line that encapsulates part of the promise of the longer one typically tends to do better in both open rates and reply rates.

Better than the competition

Guess which subject line did better?

  1. “Conversation intelligence is not enough”
  2. “[competitor] is not enough”

Our hypothesis was that the latter might get more opens. It’s more specific about who we are projecting our product’s superiority against.

Surprise, surprise!

It was the former. Superiority against the market got higher open rates than superiority against the competition.

About the problem or about the product that solves it?

Guess which subject line did better?

  1. “[solution] for your team”
  2. “AI platform to [solution] for your team”

Perhaps relating to the keeping it short principle, (a) did far better in open rates. While both the subject lines talk about solving a specific problem for the prospect’s team, the former is shorter and speaks to their problems rather than our product.

The framing in the second one makes it about the platform. And that’s not a great perspective if you want to show that you care about the reader’s problems.

The optimism shines through

Including “hope” in our subject lines improved our open rates.

The positive language and the curiosity that it builds help cross the sales-y email barrier in your prospect’s minds. This is one of those areas which can get stale really quick if not used properly.

The anti-sales subject line

Some subject lines focus on not seeming sales-y while the email is explicitly sales-y. Since we were reaching out to revenue leaders, we know that they would read through any such attempts.

So for our cold emails that were specifically focused on booking meetings, we tried a new approach - being actively anti-sales-y.

“Here’s another gimmicky email [No, it’s not]” was a subject line that we used, and it worked pretty well. This subject line breaks the fourth wall in a sense (I’m not a salesperson pretending to be someone else) while also targeting a common enemy (nobody likes gimmicky emails).

It’s about providing value

Some of the most useful cold emails are the ones that provide value right out of the gate.

We shared one of our blog posts in our cold emails to prospects, and many of them reached back to thank us for the resource.

The subject line was the same as the title of the blog post. It was about “3 ways to improve your sales demos”, it was relevant to our audience, and they liked it. Here's the complete blog post on improving your sales demos. (It's actually got 6 ways, not 3).

Yes, this wasn’t personalized. But it was relevant and provided value.

And it got tons of opens and replies.

Value proposition or great offer?

Guess which subject line did better?

  1. “Free tool for [value prop]”
  2. “[value prop]”
Email subject line including the word "free" may not do too well.
Even if the product had a free sign-up, it might make sense to lead with the value first. 

Yeah, you get the hint. It was (b). This might be quite audience-specific, but the difference was immense.

People want to see the value and don’t like feeling like misers.

Free offers are great, but they should be a cherry on top of the value and not the leading reason to open (and respond to) the email.

The (in)famous break-up email

There’s lots of talk in the town about whether break-up emails work. The subject line looks like this:

“[First_name], congratulations! You’ve made it to the break-up email”.

It’s enticing, but does it work?

In our experience, it does. It got higher open rates than the entire email sequence, multiple times over, and got plenty of responses as well.

The break-up email leverages fear of missing out (FOMO) to drive higher open rates.

Some prospects read the entire chain of emails after the break-up email and realized that our offering was relevant to them. This may not have happened if the break-up email hadn’t gotten them to finally open and pay attention.

Conclusion: getting better at cold emails

Getting better at cold emails for lead generation is a continuous process.

The learnings and insights about prospect psychology stay the same.

The specific subject lines, ask, and other tactics keep evolving over time.

To keep abreast of new ideas and experiments going on in the field, we recommend following email gurus like Will Allred of Lavender (he posts helpful content every day on LinkedIn and TikTok, and knows what he’s talking about). Also, check out his blog post with Dooly.  

Also, if you are curious about how AI tools can help you write better emails, check out Lavender, Regie.ai, Copyfactory, and Jasper AI.

AI for writing cold emails and even entire sequences is evolving pretty fast, and there’s some interesting innovation happening in the area.

Have any insights to share from your own experiments with cold emailing? Do share with us!

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