4 Tips for Improving Your Email Subject Lines

Oct 7, 2019

A subject line is the first thing your users see when they receive one of your emails in their inboxes, so it is absolutely vital that your subject lines are the best that they can be for all of your email marketing campaigns.


In fact, sixty-four percent of people open an email because of the subject line, so put a lot of time and effort into establishing strong ones for your campaigns. Below are 4 tips that have proven successful for many email marketers in terms of improving open rates, raising click-through rates and even growing revenue. 


  1. A/B Testing


Because each business’ audience responds differently to different techniques, it is always helpful to perform an A/B test with email subject lines. To do this, divide your email recipients into two groups (or more, if you’d like to try out a handful of subject lines and your subscriber list is long enough). Remember to divide randomly.


Send them exactly the same email and analyze, not only open rates, but click rates too. Sometimes, one subject line may not only amp up open rates, but also enhance click-throughs. In order to ensure accurate results, it’s important to only have one variable, which in this case is the subject line.


  1. Choose Vocabulary for Strong Subject Lines


When experimenting with subject lines, different marketers prefer different techniques, but there are a few basic strategies that have proven successful for many brands in the past.

  • Include numbers: Users are much more likely to open an email that includes specific numbers in the subject line. So, for example, “Only 5 days left to sign up for the biggest event of the year” is more compelling than “Remember to sign up for the biggest event of the year.” This rule generally holds true for anything involving dates, percentages, money, etc.
  • Use action words: It’s just like your middle school teacher taught you, using action words makes for more exciting writing. That means embracing strong verbs in phrases like “sign up,” “race to,” “respond now” and “you forgot.” That also means ditching the more boring verbs, such as “is” “are” and anything too passive. In a subject line study, emails that featured the word “alert” saw a 38 percent higher open rate and those that spoke of “free delivery” increased by 51 percent.
  • Address the reader: Instead of talking vaguely, talk specifically to each reader. Ask them to sign up for things or relate topics directly to them. Instead of writing, “Ways to live a healthier life,” you can write, “5 ways you can live a healthier life.”
  • Ditch the boring stuff: Anything too technical sounding is sure to wind up in the trash in no time. Subject lines with the word “report” in them saw a 24 percent decrease in open rates. Ones that featured “learn” fell by 36 percent, and email subject lines that talked about “intelligence” or “forecasts” also saw lower open rates than average.


  1. Avoid Sounding too Spammy


Not only will spam-like subject lines hurt your email campaign by decreasing open rates, but this type of subject line also has the ability to land you in the spam box instead of the inbox, meaning next to no one will even see them.


Mail providers such as Google, Yahoo and Hotmail identify potential spammers and avoid showing that content to their users. Hit the spam box one too many times and your IP address could be blacklisted all together, meaning that you won’t reach users’ inboxes or spam boxes. To sound less spammy in your subject lines, avoid these words:

  • Buy now
  • Cheap
  • Sale
  • Free
  • Act now

There are always cases where it’s acceptable to use these words, and that’s when you’re actually making a legitimate offer (like in our “free delivery” example in the point above). That said, if you are using any of these potential spam words, use them sparingly. The only thing worse than a low open rate, is no open rate because users aren’t even receiving your emails. 


  1. Use Dynamic Content


Take advantage of today’s smart email systems by utilizing helpful tools, such as dynamic content. Dynamic content pulls in information about your users and adjusts its wording, and sometimes even total content, to fit direct guidelines that you, the email marketer, sets.


Dynamic content can be used in an email campaign’s send schedule, subject line and body. Here are a few ways to take advantage of pulling dynamically in your emails’ subject lines:

  1. Pull in a user’s name to customize the subject line.
  2. Divide by age and target with subject lines accordingly.
  3. Send different subject lines to men and women.
  4. Target users through subject line by last use or last order dates.
  5. Take a tip from Amazon and use previous orders to target market in your email campaigns’ subject lines.

Seventy-eight percent of CMOs think that custom content is the future of email marketing. It will allow companies to cater their targeted marketing approaches to individual users based on age, gender and customer history. But custom content begins with custom subject lines.


Today, nearly all main email providers allow the opportunity to utilize these dynamic subject lines to better customize emails for subscribers. If you don’t already use dynamic content, contact your email provider today to explore how you can start incorporating it into your own email campaigns.




In order to carry out these subject line ideas for improvement, you need some serious resources dedicated to your company’s email marketing. Did you know that only eight percent of companies actually have a team dedicated to email marketing? Yet in some companies, email marketing is responsible for nearly 25 percent of a company’s revenue.


Emails are an excellent source of revenue because they’re essentially free. Sure, you pay for an email provider’s services, but outside of that you’re not really paying for advertising. Because of the low cost of sending emails and the high potential pay-off, an effective email campaign has the ability to make any company a lot of money. So when designing your next email marking campaign, don’t forget the importance of a strong subject line.