Subject lines for employee emails are pretty important.

Even though they are just a few words, they have an extremely important job--get the email opened.

But how do you make sure your subject line is up to the task?

What makes a good employee email subject line?

These are excellent questions.

To answer them, we turned to data.

How long should my subject line be?

To start, we analyzed some data on subject line length to see if that made a difference in the open rate of employee emails.

Internal email subject line length graph - by Bananatag

Looking a the Subject Line Length graph we can see over 50% of subject lines lengths on emails sent are between 20 and 50 characters.

The average length sits at 48 characters.

When we compare open rates to subject line length we can see that there appears to be a slight trend of open rates getting lower as the subject line gets longer. However, if we look at where the bulk of subject line lengths sit (between 20 and 50 characters) we see there is no difference.

Open rate by subject line length- Data by Bananatag

Overall, subject line length doesn’t have a huge impact on open rates.

Internal communicators can rest assured a short subject line will likely make the same impact, even with other email open factors removed from the equation.

So now that we know that subject line length doesn’t matter much for internal email open rates, let’s see how different words in subject lines affect open rates.

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The Most Commonly Used Words in Subject Lines

To figure out what makes a great internal email subject line, we pulled some data on what subject lines internal communicators were already using for their employee emails.

Here’s a cute word cloud showing what we found:

Internal Email Subject Line word cloud by Bananatag

As you can see ‘News’ is clearly the most used word in employee email subject lines by a longshot. Words like ‘update’, ‘inside’, and ‘weekly’ aren’t far behind.

Months of the year also seem to be popular words in internal email subject lines.

Now at first glance, it doesn’t seem like these are riveting words. They don’t exactly peak most people’s interest.

But do they work?

To find out, we did some research on how certain words in a subject line can affect open rates.

Months of the Year in the Subject Line

When we examined our data we found the most obvious correlation between common subject line words and open rates for internal communications were months of the year.

Internal email subject line graphs with months included by Bananatag

'December' came out on top with an 86% open rate.

We can speculate that at this time of year employees are more interested in what's going on at the company like holiday hours, the company end of the year party, bonuses, budgets, etc.

The summer months (June and August) experienced the lowest open rates. This could be because more employees are out of the office on summer holidays.

So does the month being in the subject line really matter?

But we’re inclined to say that these correlations are more likely to be due to the time of the year than the subject lines. Which leads us to our next question:

How much does subject line really matter?

If you believe mainstream marketing wisdom, subject lines will make or break your opens. In one study, 47% of people said the subject line is the main reason they open an email.

That being said, internal communications is obviously different than B2B or even B2C communications, because employees are generally encouraged to open pertinent internal emails. 

But in order to know if the company email is important, they need to know what the email is about—that’s where great subject lines come in.

Why you need a great subject line for your internal emails

Your newsletter or company-wide email is competing with, on average, 147 other emails that your employees receive in their inbox every single day.

Now the stats vary on this, but most research we looked at showed that the average office employee is receiving between 88-147 emails per day. And almost 50% of those emails are spam.

That sure is a lot of competition.

The Good News: For internal employee emails, open rates are actually pretty high. Our research showed that companies using Bananatag had up to an 89% open-rate. Most marketing emails score open rates of about 30%, even with all that effort they put into epic subject lines.

The Bad News: If you are sending an important employee email, missing out on 11% of your employees is kind of a big deal. On an email list of 1000 people that is 111 people who will not read your email! Maximizing your opens is, therefore, essential.

The best employee email subject lines

Based on our research, there isn’t any direct correlation between particular words and higher open rates. But that doesn’t mean your subject line isn’t important and it doesn’t mean there’s nothing you can do about it.

The best subject lines to reach your organization’s employees are going to be unique to your organization. If you want to start improving them and finding out what works for your organization, check out our post on the 5 best tips for writing the perfect internal email subject line.