How to Write Email Subject Lines that Boost Your Open Rates

Reading Time: 12 minutes

Experts estimate that on average, nearly 333.2 billion emails are sent and received daily.

Source: Hubspot

Over the years, Email marketing has only grown more popular. With these mind-boggling email marketing statistics in mind, it is hard to ignore the potential of a great email marketing campaign. Good email subject lines can make a powerful impact on your readers. They’re the most vital part of an email marketing strategy.

Since email inboxes are inundated with hundreds, maybe even thousands of emails every day, catchy and effective subject lines that break away from the clutter, are more important than ever. Spending a little extra time on your email subject lines will not only boost email open rates, but also avoid your mail ending up in the spam folder, and maybe even prompt your subscribers to respond to your marketing campaigns positively, leading to higher conversions.


Personalization is a step up from segmentation. It is when you include specific details about the person receiving the email in the content. Most common examples would be addressing the person with their name, including personal details like their birthday, company name, job title, or reminding their cart activity. However, personalization goes far beyond the below:

– Welcome a new subscriber
– Thank a person for their purchase
– Remind them to finish the video

Both the timing and the message make these types of email subject lines so effective. Research indicates that emails with personalized subject lines generate 50% higher open rates.

Test, Optimize & Repeat!

Here is a case from Pixl that proves every industry needs a custom strategy derived from data and testing. The Industry average for open rates is almost 12% when it comes to Real Estate related Email Marketing, but PIXL observed that we could boost the open rate to upwards of 20% when we use non-personalized, formal, to-the-point subject lines. One reason for this is that, when it comes to high-ticket products, people want to see genuine, non-spammy, trustable corporate communication. Testing is the best way to get data on what will work for your product.

Creating a sense of urgency

This is one of the oldest tricks in the marketing handbook. But it still does wonders when writing effective subject lines in email marketing. To grab someone’s attention and persuade them to reply/ respond, you need to create a sense of urgency in the minds of your subscribers. Also, people often respond to the possibility of losing out on something, rather than to the promise of gaining something. Always consider using action phrases that convey a sense of urgency and clearly state what the offer is about. Mail chimp found the following benefits of using time-sensitive words:

Usage of words in an email

According to Boomerang, emails with less than 300 words have the best response rates at just above 50%. It is easy to go overboard when writing about the features and benefits of a product, but always check if the content aligns with your objective. We want the readers to be curious about the product and click on the CTA and not read and forget. Keep it short, with just enough information to arouse interest in the readers, nudging them to hit on the CTA and follow the path to conversion.

Avoiding using spam trigger words

Subject lines that are aggressively sales-oriented are often more likely to be marked as spam. This means you should avoid using overly promotional keywords and multiple exclamation points like “Free”, “Hot”, “Make Money Fast”,  “!!!”, “???” etc. Some of these may seem like completely innocent words, but they are also words that are often used in spam emails.

Preview Text

While it isn’t technically part of the subject line, the preview text appears just near it. It is a bonus feature and a chance to grab the reader’s attention. You can use enticing preview text to persuade the reader and give your email campaigns an extra push. Keep in mind that if you keep the preview text blank, it will automatically select from the body of the email text. So it is best to make good use of this feature.

Usage of numbers

Just as numerical lists are effective in blog titles numbers can be effective in email subject lines. In addition, incorporating numbers into your subject line creates focus, as our brain is naturally drawn to digits. Subject lines that include numbers, if you back that number up in your email body, convey a sense of credibility. For example, ‘5 Reasons To Buy XYZ’, ‘9 Must-Have Metrics For HR’, ‘3 Ways To Make Your Small Company Look Big, etc.

The best subject lines are built around your target audience and brand. However, you can definitely get some ideas by looking at what’s working for others. The subject line of an email is the single line that people see when they receive your email. This one-line text can often determine whether your email is opened or sent straight to the trash, so make sure it is optimized for your audience.

Still, have doubts about how to create optimized subject lines for email marketing? Pixl has achieved high open rates for various industries by using custom strategies and we can help you do the same.

Register with us today and we will help you achieve higher open rates and conversions in email marketing.