Best Email Subject Lines for B2B Prospecting

Believe it or not, around 50 percent of people choose to read, ignore, or flag emails based solely on the subject line. No matter how perfect your copy is, a single subject line mistake can tank your entire campaign.
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After pouring over metrics, strategizing with your team, and crafting a pitch-perfect copy, your amazing marketing email is almost ready to send. You’ve packed this puppy with emotional content, a smart and engaging CTA, and some fun, interesting photos. It seems perfect. But what about the subject line? Believe it or not, around 50 percent of people choose to read, ignore, or flag emails based solely on the subject line. No matter how perfect your copy is, a single subject line mistake can tank your entire campaign.

So how do you create the perfect subject line? You need something that inspires decision-makers to open, read, and consume your entire email. And you only have a few words to make that happen. Here’s how to win at email marketing with subject lines.

The Surprising Importance of Subject Lines

The average person receives over 
120 emails every day. Only 40 of those are business-related. The rest are mostly marketing emails from your competitors. Yeah. That’s a lot of emails. So, it shouldn’t be all-too-surprising that the average open rate for emails (across industries) sits at a meager 16 percent. In other words, the average email gets opened by around 16 out of every 100 prospects you attempt to reach. In the B2C space, this isn’t immediately damaging. But as a B2B company investing in high-quality, highly-vetted leads, reaching less than a quarter of your target audience is a big problem.

You want to engage and nurture every prospect in your pipeline, reaping a tempting 50 percent increase in sales-ready leads along the way. But you can’t nurture someone you can’t reach. Every ignored email is a missed nurturing opportunity. And the moment a prospect categorizes your email as spam, your entire nurturing campaign is on life support.

Here’s the great news: your subject line can prevent leads from marking your email as spam (69 percent of emails are marked spam due to the subject line alone) and tempt them to open your email. Here’s the bad news: most B2B companies struggle to create effective subject lines. They always say don’t judge a book by its cover. Yet over 50 percent of people choose books based on the cover jacket. The same goes for emails. You can write the world’s most conversion-ready email. If no one opens it, it’s the world’s worst email. You have seconds to tempt your prospect to open your email. You need to make them count.

So how do you write a subject line that converts?


How Not to Create an Email Subject Line

For a moment, let’s pretend we’re on a path of self-destruction and loathing. We want to destroy our business, annoy our leads, and fulfill our deepest and darkest fantasies of living in the chilly, icy mountains of remote Canada without a penny to our names. So, how do we write an email subject line so utterly terrible that it eradicates all hope and takes a sledgehammer to our end-of-year revenue?

1. Use A Ton of Words and Unnecessary Prose

Who doesn’t love reading an entire book’s worth of words before they open an email? Research
suggests you should keep your subject line under 41 characters and 9 words. Remember, prospects have hundreds of emails to sift through. And the average attention span is around 8 seconds. So, let’s make a 31-word email line stuffed with a bunch of trigger words like URGENT, AMAZING, and BUY NOW. That should do it.

We’re well on our way to digging the remnants of our filing cabinets out of the rubble that used to be our business.


How can we possibly make our email stand out? Wait! What if we used caps lock to capitalize every word? It would be like we were right next to our customers, screaming sweet nothing’s gently into their ears. In fact, a single capped word drops response rates by
over 15 percent. So, if we cap the entire subject line, virtually no one will read our email. Better yet, they’ll probably flag it as spam — forever dooming our emails to life in the dusty, rotting corners of the never-read spam folder.

3. Bringing out the Buzzwords

Every industry is dripping with buzzwords and acronyms, so let’s shove those in our subject line. “Are you ready to boost your ROI with IoT and ML tech stack point solutions?”

Wait… what is ML again? And what’s the difference between a point solution and a normal solution? Who knows! Who cares! Email subject lines’ sole purpose is to showcase our niche knowledge of the industry we’re in — not to inform and grab attention.

4. Abuse Trigger Words

Did you know that emails with the word “free” are opened 10% more often? Makes sense. Who doesn’t love free stuff? So, let’s shove the word free in the subject line without actually giving the user any free stuff. I’m sure our customers will absolutely love it when we game the system. Who wouldn’t be downright thrilled to read an email that has nothing to do with the subject line?

How to Write Winning Subject Lines

Jokes aside, writing an email subject line is challenging. There are terrible strategies like the ones above, but most companies simply fail to secure open rates because their subject lines are boring, lengthy, and emotionally void. Here are 4 tips for creating world-class subject lines.

1. Personalize Based on Existing Data and Lead Behavior

Personalization is one of the single most powerful tools in the marketing arsenal, and emails are no different.
74 percent of marketers say personalization increases email engagement rates, and personalized emails increase transactional rates by 600 percent. In fact, personalized emails generate an average ROI of 122 percent. So, it shouldn’t be surprising to learn that emails with personalized subject lines see 26 percent higher open rates.

You should use existing customer data to perform baseline personalization. This can be something as simple as adding a name or as complicated as using past behavior to craft the line. For example, you could trigger a personalized email when a user downloads your whitepaper. A few weeks later, you can send an email with a subject line reminding them of that action.


  • Hey John. How have you been?
  • Ready to learn more about personalized email marketing? Hint: this is based on a content consumption trigger

2. Use Click-worthy Keywords When They Make Sense

There are plenty of high-value keywords that boost open rates. Some examples include: Welcome, First Name, Urgent, Weekend Only, Sale, Special

Some of these keywords invoke FOMO, some build personalization-centric trust, and trigger savings-based instincts. But you should only use them if they make sense in the context of your email. Never use the word Sale in your subject line if there isn’t a sale. And definitely don’t use urgent unless the email is urgent (in the context of your business).

Every niche has different click-worthy keywords, and you may need to do some A/B testing to discover which words work best for your prospects.


  • Urgent! Our 5-day sale ends tomorrow
  • Welcome to the future of marketing


3. Keep It Short

In a world where marketers are constantly battling to find the next catchy phrase, luring subject line, and emotional trigger, going back to the basics can be a refreshing change of pace for prospects. Remember, most prospects are used to opening work emails with very basic subject lines. So, many associate these short subject lines with importance. In other words, most marketing emails are clever. In turn, many customers associate clever and catchy phrases with marketing content. Short and simple can make your content seem more important and less “salesy.” This is backed up by some lengthy research. Mailchimp found short and sweet subject lines to be the single most effective at garnering opens.


  • Thanks!
  • Enjoy the content
  • We’ve just updated


4. Be Emotional

It’s a common misconception that B2B marketing should be bland and business-centric. Between finding decision-makers, dealing with purchasing committees, and navigating the world of third-party consultants, B2B marketing can feel very suit-and-tie. But it’s not. According to Google, B2B buyers are
50 percent more likely to buy a product/service if they see the personal value, and they’re 8x more likely to pay a premium.

Your subject line is the perfect place to invoke emotions. Happiness, fear (of missing out), and excitement are all perfect subject line emotions.


  • Don’t miss this new deal!
  • We loved hearing from you John
  • You have a problem John


Want to Build World-class Email Campaigns?

Email marketing is hard. You have hundreds of competitors flooding your high-value decision-makers with content. You need to stand out. At Sapper, we help companies build intelligent marketing campaigns using automation, sales enablement, and industry-leading email strategies. Contact us to learn more.

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