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Are Bad Email Subject Lines Costing You Employee Engagement?

First impressions matter—even in emails. The subject line represents a critical piece of the employee engagement funnel. In this post, we’ll share how we help customers write subject lines that boost employee engagement in content by an average of 45%.

Why are subject lines so critical? Though often neglected, those 50 to 75 characters of your email are the first thing that employees see. The subject line helps employees rapidly filter their crowded inbox, which means that having a good one is the difference between capturing employee attention and ending up in the digital trash.


A few of our customers recently discovered this first hand. On Airbo, companies send an email to employees to let them know that there’s new content for them to read. But if employees don’t open the email, they don’t know there’s new content, and they don’t participate.


When customers want to increase the number of employees that participate in Airbo, the typical instinct is to do additional raffles, promotions, and drastic changes in content. Our customers are surprised when we suggest they start with simple tweaks to the subject line. With improved subject lines, our customers’ average participation rates increased 45% within 4 weeks.


So, how do you write an effective email subject line?

Here are four best practices we’ve found over the years:

1. Keep it short and sweet

Try to limit your subject line to 50−75 characters. This makes it easy for employees to quickly read and understand.

2. Say exactly what’s inside and why it’s valuable to the employee

Make sure employees understand how the content of the email will benefit them. The internet has become so saturated, that people have to rapidly decide if something matters or not.

But that doesn’t mean your headline can’t be surprising, entertaining, or create a curiosity gap to get users to click. A great headline is also interesting.

Example: If employees can earn a benefit for completing their biometrics, use a subject line like: “Want an extra $250 in your HSA? Complete your biometrics.”

Here, we’re able to pose a question that gets attention, but are also very clear about the purpose of the email.

When an email has multiple topics, include all of them in the subject line. An employee is likely to be interested in at least one of the topics.

Example: One of our customers in the tech industry increased their email clicks by 33% in one week by changing the email subject line from “Your New Tiles are Here” to “Meet our new Marketing Assistant, 401(k) info, and more!”

3. Channel your inner Buzzfeed writer – use numbers

Have you noticed that just about every article on Buzzfeed uses numbers in the title? As you may have suspected, it turns out that people strongly prefer titles with numbers in them.


Example: If you send out several Tiles at once during Open Enrollment, use a subject line like: “4 Tiles with your 2020 Open Enrollment To-Dos”

Numbers can also help indicate how many colleagues have completed an action. This induces “fear of missing out” and encourages employees to click on the email if they haven’t completed the action.

Example: If you are doing an HRA promotion, use statistics to help drive participation with a subject line like: “Over 375 of your colleagues have completed their HRA. Have you?”

4. Keep subject lines fresh

Finally, repeating the same subject line week after week is a recipe for deletion. Employees are more likely to delete an email with a subject line that they’ve previously seen. It’s important to establish a brand, but each new email’s subject line should preview what is inside.

Not sure which subject line your employees will respond to most? Consider using A/B testing. On Airbo, customers are able to test out different versions of subject lines on the same email with A/B testing. They can see which subject line receives the greatest number of clicks and can use this information when writing the subject line for their next email.

To Summarize:
  1. Keep it short and sweet
  2. State what’s inside and why it’s valuable to the employee
  3. Channel your inner Buzzfeed writer – use numbers
  4. Keep subject lines fresh