Email Subject Lines: Everything You Need to Know (Cognism Guest Post)

The World Before Email Subject Lines

In 1971, the American computer programmer Ray Tomlinson sent the first email. Sent from one computer to another in the same room, the message consisted of a string of unconnected letters; in Tomlinson’s own words, “something like QWERTYUIOP.”

From these humble beginnings, a new era of human communication began. Little did Tomlinson know that over the following decades, email (electronic mail) would grow to become one of the most popular and ubiquitous platforms for people to communicate with each other.

Today, email is a staple of personal and business communication. This year, it was estimated that there are 2.8 billion email users worldwide – that’s over one-third of the world’s total population!

As more people started using email, so the format of the email itself changed. That very first email from 1971 didn’t contain a subject line; today, every email provider and platform includes subject lines. They have become a core element of the email format.


Why do email subject lines matter?

For business, email subject lines are all-important. They can make all the difference to an email being opened or thrown into the “Deleted Items” folder. Last year, approximately 269 billion emails were sent and received each day. This is expected to rise to over 333 billion emails by 2022.


Top five tips for email subject line success

With so much competition out there, it’s vital for an email’s subject line to stand out. But how can you go about doing this? Luckily, we have some expert advice on hand. Cognism’s customer success team are masters of the outbound email. They’ve put forward their top five tips for making your subject lines as effective as possible. Read on and be inspired!

  1. Keep It Short

What is the ideal length for an email subject line? Before thinking about this, it’s worth looking at how people are reading emails these days. Mobile devices are now a very popular means of reading emails, with higher open rates than webmail and desktop (in the first half of 2018, mobile opens accounted for up to 47% of all email opens).

So a sizable chunk of email users now consume emails on their mobile or tablet devices. With that in mind, it’s best to optimise your subject lines so they can be easily read on mobile. If your subject line is too long, some of the text will be cut off. The recommendation is to keep your subject lines short – 50 characters or fewer.

  1. Use Action Verbs

Think of your email subject line as similar to a call-to-action, in that you want the language to draw people in and entice them to click. Use action verbs at the start of your subject line to create urgency and excitement. Here are some examples:

  • “Build your online presence…”
  • “Grow your sales pipeline…”
  • “Find out how…”
  • “Start your free trial…”
  • “Join us today…”
  1. Be Honest

When it comes to crafting an effective email subject line, honesty is always the best policy. The subject line should summarise exactly what the email is about. Avoid vague or ambiguous language. Instead, be clear and straightforward. Focus on one action and indicate how it can help the recipient.

Use concise, simple, understandable language. The easier your subject line is to read, the more chance your email has of being opened.

  1. Use Numbers and Statistics

Cognism customer success suggests adding numbers or statistics to your email subject lines. Including data in your subject lines adds authority to your message and helps to build trust between yourself and the recipient.

So for instance, if you’re advertising an event, instead of writing, “Register today for our 2018 event”, try: “Join up to 1,000 people at our 2018 event.”

Or, if you’re promoting a sales acceleration service, instead of writing, “Boost your sales with us”, try: “Boost your sales by 25% with us.”

See how much better the subject lines read with the numbers included? They demonstrate a clear benefit of the product and the value for the recipient.

  1. Get Personal

Personalisation is fast becoming a popular concept in email marketing. And with good reason – it gets results! The digital marketing guru Neil Patel has identified that emails with personalised subject lines see an 82% increase in open rates.

So don’t be shy in using the recipient’s name in your email subject line – or if you don’t have that, their company name. Personalising your subject lines in this way makes it much more likely that your email will be opened.

For example, you might write: “Increase Company X’s monthly sales by 50%”, or “James, download our free ebook today.”


A/B Testing

One final tip from Cognism’s customer success team – always A/B test your emails! The above advice is a great place to start, but what works well for some companies may not work well for others. Experiment with your subject lines and see what works best.

Send out emails with different styles of subject lines. Track the results and see what difference, if any, subject lines make. What gets better open rates, shorter or longer email subject lines? Using action verbs or not using action verbs? Including numbers or not including numbers? A/B testing will tell you how your audience is responding to your subject lines, meaning that you can quickly make adjustments and improve your performance.



I asked Kristapor Giragosian, Cognism’s VP of Customer Success, what he thinks constitutes a good email subject line. He had the following thoughts:

“My advice would be to take time crafting your subject lines. Spend just as much time on them as you would writing the email. Always A/B test and find out which style of subject line gets the highest open rates. Write two different subject lines for the same email. Send each email to a different segment of your contact list and see which one performs better.”

Does your business have any guidelines for writing email subject lines? Have you found A/B testing useful? Be sure to let us at Cognism know!

Joe Barron is the Content Writer for Cognism. Did you like this article? Do you have any thoughts or comments? Contact him at