How to Write Subject Lines That Actually Work

The subject line of your sales email is the most important thing to nail. After all, if it doesn't get opened, it doesn't get a response. Simple as that. Or to borrow the baseball analogy, you can't hit the ball if you don't get up to bat. But you already knew that, which is why you clicked on this article. 

Successful subject lines do one thing and one thing only: pique curiosity. It's the curious mind that clicks on an email. And fortunately all you have to do in order to come up with good subject lines is think about your own behavior. 

How to pique curiosity

When I check my email first thing in the morning I go through and archive as many emails as I can. My brain looks for patterns in the subject line and archives anything that screams sales, marketing or spam. Fortunately, most sales people are surprisingly lazy in their wordsmithing and write subject lines like "Looking to connect with you about marketing automation software." 

In that morning frenzy to clear my inbox my brain looks for patterns. When it reads "connect" and "marketing automation" it assumes that someone from Marketo is reaching out for the 100th time. And considering I am a happy Hubspot customer, I archive it. In other words, I'm not curious, therefore I don't even open it. 

The emails that I don't tend to archive at first sight fall into a couple categories:

  • Internal emails (e.g. "Follow up from marketing huddle")
  • Action item emails (e.g. "Wistia credit card declined")
  • To-read (e.g. "The latest from Tom Tunguz's blog")
  • Calendar invites (e.g. "Invitation: Call with Hubspot CSM")
  • Anything that looks "interesting" (more below)

The last category is the one that you — the sales rep — are looking to be bucketed in. You're probably not going to get in my "internal emails" bucket. And unless you're a better writer than Seth Godin, you're probably not getting in my "To-read" bucket. But if you pique curiosity you can get into the "looks interesting" bucket. So what are examples of this?


"Meeting this week" - Think about what your prospect may think when they read this subject line during their morning archive frenzy. Maybe it's someone cancelling on a meeting. I should open that. or I have a lot of meetings this week. Which one is this referencing? It piques curiosity. However since you are presumably trying to get a meeting the subject line isn't misleading or distrustful. 

"Google Ventures portfolio company" - This was one of my highest performing subject lines of all time. I reached out to a group of CEOs who share the same investor (Google Ventures) as Highfive and asked them to introduce me to the person who I could speak with about video conferencing. Roughly ~20% responded on the first email. Why? It piqued curiosity. It's like someone mentioning your college or high school in the subject line. Of course you're going to open it. 

"{{company_name}} on the INC 5000 list" - Another high performing subject line was the mention of company names on the INC 5000 list. We scraped the list of companies and passed them to virtual assistants who gave us a list of prospects and then sent them all an email with the above subject line. And the open rate was huge! Who doesn't want to read about their company on an honorable list? It's like seeing an email with the following subject line "{{enter_son's_name}} on the honor roll" (1)

While all these subject lines worked for me, it's important that you don't copy them verbatim. And that's for two reasons: first, each business finds success in different ways because every business has a different product offering and group of prospects they target. Secondly, every marketing and sales "hack" has a half life because prospects grow callous to the same practices. At one point "Free trial!" in the subject line probably worked. But do you still open those emails? 

I encourage you all to try out different subject lines and see what works best for you. For Barack Obama it was "hey" and for me it was "Google Ventures portfolio company." I guarantee it will be different for you. 


(1) It's worth mentioning that the click to open rate on this was disproportionately low, likely because it was misleading. The email was less about them, and more about us, and therefore I lost their trust (and probably angered some prospects).