Dark-skinned hands typing on a laptop visualizing a seller writing a cold email

How to write good email subject lines in B2B sales

Your prospects inbox is crowded. Emails often get overlooked. You need to stand out with a creative subject line. Here's how to do it.
Ryan O'Hara

You could write the greatest cold email in the world, and it won’t matter if the subject sucks.

We’ve hosted a ton of “RateMyPitch” live cold email breakdown sessions that help reps write better cold emails. We’ve even launched an AI outbound message generator, Scribe, which can easily write a good email subject line for you.

Throughout our journey to help sales teams improve their prospecting efforts, one of the most popular questions people always ask us is, “What subject line should I use for my cold emails?

Let’s break down what constitutes a good cold email subject line in B2B sales. 

Your prospect's inbox is probably a mess

5 tips for writing good cold email subject lines

  1. Good email subject lines should be vague enough to pique interest
  2. Good email subject lines should set the expectation of your cold email’s body copy
  3. Good email subject lines should be personalized
  4. Good email subject lines should not be selfish
  5. Good email subject lines should describe an email you’d want to receive

Subject lines you should use for cold emails

Before we get into the details of the tips above, we’d like to provide some quick commentary on how we grade subject lines and why many BDRs, SDRs, and even the most senior account reps are doing it wrong. 

Former LeadIQ Chief Evangelist Ryan O’Hara notes:

“When I did prospecting at Dyn, I always tried to hold on to subjects that worked to produce opportunities. Doing this allowed me to become a better prospector since we didn’t have tools like SalesLoft or Outreach back then tracking open rates, replies, etc.”

Luigi Prestinenzi, Co-Founder & Head of Growth at Sales IQ Group, says the subject line for your cold emails have to be clear. Has be to short and to the point, usually recommend 3-4 words.

"Personalization is key: keep it short, keep it sharp. Make it about the problem you are helping them solve and don't make it about you."

The goal of your email is to get a positive reply, not an open. Anyone can get a 99% open rate, but if you are trying to get a positive response that starts building a relationship, the real thing to track with subject lines is replies.

Using this as a foundation, some of the biggest opportunities we’ve seen reps get made it easy to get replies from big names, not just small startups.

Good subject lines should be vague

We see so many people shoot off their company’s best bullet in the subject of the email. Where then is the incentive to open it and ultimately reply?

Let’s use an email from one of our own Business Development Reps to show as an example of why a vague email subject line can increase reply rates.

Jim (our BDR) found a prospect that was wearing a Hawaiian shirt and lei on LinkedIn that was a good match with our ICP (Ideal Customer Profile). He decided to use that angle to start a conversation with the prospect.

Screenshot of an email personalized to prospect's profile photo on LinkedIn (email content in caption)
Email content reads Subject: King of the Luau | Body: Hey Tim, Rocking the leis on LinkedIn man, awesome. Hope you were holding a Mai Tai too. Got a quick question actually - wondering what your team is doing for prospecting at the moment. I was thinking we might be able to help you find contact info for some new prospects. We've got a nice, smooth workflow with stuff like Salesforce and Outreach, so if you're using those even better. What do you think about chatting sometime?

A vague subject line is a great way to use curiosity to draw someone in to open and read your email. In many ways, an email subject should be like a personalized version of link clickbait. 

Don’t be annoying clickbait, but think of the curiosity clickbait uses to draw interest on social media. How often have we all clicked on an article that had a vague headline off Twitter or Facebook. They got you didn't they!?

Instead, give a hint about the content that is going to be in the email body copy. 

Good subjects should set the expectation of your email’s body copy

Remember how we just compared a good email subject to clickbait? Clickbait sucks. You want to mimic clickbait, not act like it. 

The reason it sucks is that, more often than not, the headline is deceptive, and you’re ultimately disappointed after you read the entire article. You never want to do this to a prospect. 

The best part of Jim’s email subject that we showcased isn’t just that it’s vague; it's that the body of the email matches the expectation.

The subject line mentions a Luau (“King of the Luau,” in case you missed it earlier). 

Jim brilliantly didn’t sell out and just pitch LeadIQ either. He meets the prospect's expectation by bringing up the LinkedIn picture, which featured things we all would see at a Luau. 

How angry do people get when they expect something to be a certain way and that something disappoints? That same experience applies to email subjects. 

Good subjects should be personalized

The fact is, the biggest advantage a human being has over automated marketing emails is that when we are prospecting, we can personalize to anything at that moment. 

Too many prospectors fall into the trap of trying to find one subject line that can apply to thousands of people. 

When trying to figure out what to make your cold email about, find some angles that focus on the human you are prospecting to first. If you can’t find an angle, you can use the company as a backup. 

If you’re looking for a great example of using personalization in a cold email subject line, look no further than one of our own customers, Wilson Lee from Boomtrain. After some research, Wilson would routinely personalize the subject of an email with the name of a band the prospect likes. 

The result: Often, a phone call to start relationship building. 

The point of writing prospecting emails is to reach out to people and start a conversation. As sales teams and recruiters, we must stop looking at marketing emails as textbook examples of what to send. Marketing emails have their own separate email structure and best practices to follow. 

A good marketing email ≠ a good cold email. 

Good subjects should not be selfish

The best subject lines are unselfish (same for the email body copy). What do we mean by this? Sorry to disappoint, but your prospect doesn’t care about your company’s name, awards, or achievements. So why do we keep using them in prospecting emails? 

Using a company name, brand, or feature in an email subject just sets the expectation that the rest of the email will be about YOU. 

Guess what. You’re not the hero in your buyer’s journey, so don’t act like one in the subject of your outbound messaging. 

Emails that are about you or your company rely on luck instead of likeability to start a conversation or relationship. 

The same thing applies to publishing email content like white papers, ebooks, and webinars. Using marketing phrases that push your content is selfish as well. 

Good subjects should be something you would open

Before you hit send, simply read the subject out loud. Ask yourself, “If this came up on my phone as a notification or as an unread email in my inbox, would I stop what I am doing to read it and reply? 

If the answer is no, rethink the subject line. 

To take things a step further, use a text-to-speech reader to have your computer read your subject line out loud. You might get a different perspective on it by hearing it read out loud. 

You can also rely on AI sales tools to eliminate the tedious research of finding something to connect with your prospect. Our AI message generator, Scribe, can pull insights from LinkedIn activities, Twitter, podcasts, company facts, news, job postings, and more to write subject lines for you or at least give you a starting point to write your own quickly. 

With all that said, your subject line is important. Give it the attention it deserves. 

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