7 steps to the best email subject lines ever

woman reading email on phone
Though marketers rarely initiate email campaign strategies with a subject line, that is precisely how emails begin for the recipient. A subject line is the first thing email recipients see, and HubSpot estimates that nearly 50% of people open emails based on subject lines alone.

It’s tempting to spend a lot of time making sure the email content is high-quality and relevant (and you should!). But writing the subject line as an afterthought can make all that time spent much less effective and seriously affect your results.

If no one is opening your emails, no one sees your great content, and your email campaigns won’t be as successful. So—how can you craft the perfect email subject line? Here are a few guidelines to get you started.

Build a better email subject line

Keep character and word count low.
Character count should be at 50 characters or fewer, and word count research suggests about seven words as the ideal number for a subject line. Research varies widely on how much length really effects open rate, but if your subject line is too long, the whole thing won’t show in email clients.

Create a sense of urgency.
Emails with a deadline are 22% more likely to be opened. People don’t want to miss out on something, so applying a sense of urgency to the email encourages click.
Did you know: emails with “tomorrow” in the subject line are opened 10% more often than those without?
Pique curiosity with questions.
People are inquisitive. Encourage click-throughs by giving your audience a teaser in the subject line. By asking questions or using ellipses in a subject line, you can generate questions in the user’s mind, inciting them to open the email to find the answer.

Keep your personas in mind, and personalize.
People are 22% more likely to open an email with their own name in the subject line. Another method to keep in mind is tailoring subject lines to your marketing personas. People want emails that are relevant to them, and using their names and persona features are ways to help you achieve that goal.

In the example below, the Knot set up this message to use both my name and a countdown to my wedding date in the subject line to make the email feel extra-personal.
Be clear and accurate.
If your subject lines are clear, your audience will know what to expect, and your metrics will reflect that. Descriptive subject lines tell people what they’re going to get, and if they’re interested, they’ll open the message.

Make people want to take action.
Including action-oriented verbs in the subject line prepares recipients to take action. In the example below, Loeffler Randall created a sense of urgency with use of an action verb.
Switch it up.
Change the subject line for recurring email newsletters. Not only does it keep your readers from getting bored and ignoring your messages, but it can also help keep your emails from being filtered into the promotions or spam folders.

Bonus: More quick email optimization tips

Optimize your email preview.
The email preview isn’t technically the subject line. But used well, it can bolster your subject line. It’s the snippet that comes after the subject line in many email clients, and it can be used to provide more information and give the user even more incentive to click, like this example from an email sent by Zappos.
Send emails from someone your audience will recognize.
With email automation tools, it’s easy to customize not only the subject line but also the sender. Using HubSpot for example, you send automated emails (say, an email with an ebook download link) from the salesperson that the customer is assigned to in your database. That way, whether or not the salesperson was involved in signing that customer up for the ebook download, the email comes from someone that customer recognizes, rather than a generic email address that could be mistaken for spam.

Choose your send time wisely.
Depending on the goal of your email, send time could give your metrics a boost. Imagine you’re a mail-order meal prep service. Sending a marketing email in the late afternoon, when people are starting to think about dinner (and maybe realizing they don’t have anything to eat at home) could result in higher open and click-through rates.

Think about mobile.
55% of email is read on mobile devices. You may be designing your emails on a desktop computer, but if you aren’t optimizing email for mobile users, you could be making it harder for more than half of your audience to read your content.

Measure subject line success

Subject line success is highly influenced by your audience. What works for one target audience won’t always work with another—and that’s what makes nailing down universal email best practices so tricky. The best way to determine the most successful email subject line strategy for your organization and your audience is data.

A/B testing
Refining your subject line strategy and learning what works best for your industry and target audience requires testing. A/B testing is a test run between two versions of your email.

For example, you could conduct an A/B test for an email advertising a sale. The interior content of the email should be identical (focus on examining only one variable at a time with A/B testing), then one subject line could read, “25% off spring essentials: two days only” and the other could say, “25% off spring essentials: two days only 🌼.” Through a test like this, you can explore how emoji use in subject lines affects responses.

A/B testing allows you to evaluate every aspect of your subject lines. This list is just the beginning:
  • All caps, sentence case, title case, all lowercase, and more
  • Wording and word placement
  • Emojis
Open rate
This popular email metric measures how many people opened your message, making it a significant metric to look at when you’re evaluating your subject lines. In general across industries, an open rate of 20–30% is considered good.

Deliver email people want to get

In the end, the success of your emails comes down to one answer: do your emails provide value?

Even if you’ve done everything right when writing subject lines, user interaction will stop if what you’re sending out does not provide value. If you’ve optimized your subject lines but your metrics are still suffering, it could be time to take a step back. Take time to look deeply at your target audience, who they are, and what they want to see. A successful email strategy will meet your users' needs, and in a way that works for them.

Need help with your email marketing? Contact us

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