10 Best Practices to Write the Perfect Email Subject Line

A subject line is often the most important text in an email.

It’s what makes your email stand out among the 100-plus in the average inbox every day. It’s what motivates recipients to open the email.

How can you make a great first impression when you get into inboxes?

Learn how to not only attract the attention of recipients, but also to improve their engagement with your brand.

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1. Personalize it

There are many personalization options available for emails. You can send it from an individual at your brand rather than a generic email name like TextRanch.

The human touch is more likely to grab subscribers’ attention who see it as a more personal email, not a promotional brand email.

You can also personalize the subject line depending on the information you have about the subscriber. For example, subscribers who live in Toronto where heavy snowfall is predicted might receive an email with this subject line: “It’s snowy in Toronto – get 20% off leather jackets.”

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2. Keep it short and to-the-point

Nearly half of people prefer to access their email on a mobile device. If you write a lengthy subject line, much of it won’t be seen by mobile viewers. Most email clients won’t show more than 43 characters of a subject line in mobile view.

Most #email clients show no more than 43 characters of subject lines in mobile view, notes @EvaldasMockus via @CMIContent. #EmailMarketing Click To Tweet

Marketo found that subject lines with four words had the highest average open rates (18.26%). However, the click-to-open rate likely is more important because it encompasses both opening and clicking on at least one link – conversions. The seven-word subject lines had the highest CTO rate (10.8%), followed closely by nine words (10.6%), then six words (10.1%).

The highest average CTO rate (10.8%) happened with seven-word email subject lines, according to a @adobemarketo study via @EvaldasMockus via @CMIContent. #EmailMarketing Click To Tweet

3. Make the most of all available real estate

While the subject line should not be too long, the preview text and pre-header may be a bit longer. In this example from Clark at InVision, the subject line is “Real World: Product Design” with the preview text, “5 UX career trends for 2019. Plus, the true life of a lead product …”

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In this example, 26 characters are used for the subject line, while 68 spaces are used for the preview text.

Make sure you don’t repeat the subject line in the preview or pre-header section. Instead, explain the subject line or highlight a detail that is not indicated in the subject line.

Make sure you don’t repeat the #email subject line in the preview or pre-header section, says @EvaldasMockus via @CMIContent. #EmailMarketing Click To Tweet

4. Use numbers

Debra Jason once said: “Our brains are attracted to numbers because they automatically organize information into a logical order. Your headline is an advertisement for the content you are promoting in marketing and advertising. A single, small odd-numbered digit, like seven, for example, is like candy for your organizational mind.”

The same applies to your email subject line. Yesware studied 115 million subject lines. It found that including numbers in subject lines increases open rates and replies.

#Email subject lines with a number have higher open and reply rates, according to @Yesware #research via @EvaldasMockus @CMIContent. #EmailMarketing Click To Tweet

Numbers tell the story more clearly than letters and are visually more appealing than letters. Let’s look at two options with similar messages:

  • Top tips to lose weight right now!
  • Lose 5 Pounds in 45 Days

Which one is more effective? The second one because it sets expectations and creates a clear picture of what’s inside for the recipient.

5. Use power words

Use power words to transform boring, mundane subject lines into irresistible ones.

It is possible to trigger an emotional and psychological response from the recipient, which will be more likely to get a click to open your email. You can use power words to stimulate curiosity, appeal for vanity, build trust or develop FOMO (fear about missing out).

Arouse curiosity

Our brains are wired to respond to curiosity when presented with information that isn’t familiar. This thinking can be used to create a curiosity gap between your subject lines.

For example, ask a question: Wonder How We Make Our T-shirt Unique? Or, make a genuine promise: 7 UnexpectedHere are some ways to increase your sales.

The power words in the above examples were bolded. Here’s a long list of words that are worth your attention:

Appeal to vanity

You can tap into psychological behavior that makes people want recognition or admiration. This topic line appeals the vanity around beauty: A Dazzling Product for Skin Care That Will Make You Look Younger.

Here’s a list of vanity-appealing power words. Remember, you can use multiple power words to enhance the efficiency of your subject line too, but don’t go overboard:

Trust builds

Incorporate words into your subject line. These examples are just a few: Get Lifetime Access To Our Membership Plan or Try These Bestseller Products.

Here’s a list power words that can help you create trust.

FOMO is a good idea

Fear of missing out is directly proportional with loss aversion. It is easy to communicate clearly what recipients stand for by not opening emails. As this example illustrates, 5 Hacks you Must Know When You Buy Jeans.

These are the words you should use in your subject lines in order to create a feeling of FOMO.

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6. 6.

Sharing something of value is a great marketing strategy. Let recipients know what they’ll get by opening your email. Make your offer attractive and compelling.

You don’t need to use the word “free” to create value. Offer a discount, share a success story, and so forth. These are just a few examples.

  • Check Out Our Awesome 20% Mother’s Day Discount
  • Get a 10% discount on your first purchase
  • Watch Rebecca Get Rid Of Her Acne with Our Serum

Be honest about your products or services, and don’t make any false promises to earn an open.

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7. 7.Make an announcement

Announce new product releases, limited editions, updates or upcoming events within your organization. Send it to your email. In your subject line, convey that feeling of exclusivity or insider news.

  • Be the First to Order Tesla’s Model 3, Available Now
  • Exclusive Preview of 5ThAnnual Black Friday Boot Camp

8. 8.

Experian research has shown that emojis are 56% more likely to be opened than text lines. Recent analysis by Search Engine Land and others shows that emojis can cause recipients to not open an email.

Don’t assume emojis in your subject lines will prompt opens, says @EvaldasMockus via @CMIContent. #EmailMarketing Click To Tweet

If you want to test the impact of emojis in your subject line, make sure they’re relevant to your message and easily understood by the recipients like this for gift-giving events:

They can be placed at the end, in between words, or even in the preview text. But don’t overdo it, and make sure to analyze your open and click metrics to see if they’re having a positive impact.

9. Avoid shouting

Have you ever received an e-mail with a subject like this? OPEN NOW—YOU WILL BE SURPRISED!

Many brands still do to get their subscribers’ attention. However, this practice isn’t good and can get your emails flagged or marked as spam. Instead, be more gentle.

While all caps should never be used, test which case – sentence, title, or lower – resonates best with your audience. Here’s how those options would appear:

  • In just 4 weeks, you can increase your e-commerce sales (sentence case).
  • You can increase your E-commerce sales in just 4 weeks (title case).
  • You can increase your ecommerce sales in as little as 4 weeks (lowercase).

10. 10.

Last but not least, make sure you test your subject line before you send your email to one recipient. It is possible to test it with a friend or colleague and get feedback on how engaging the subject line was. You also can use tools such as my employer Omnisend’s subject line tester, Net Atlantic’s, or another.

Here are some suggestions to test subject lines:

  • Test at least 20 variations.
  • Identify the top three.
  • You can use each one in your campaign by A/B testing.
  • Analyze the winner.
  • For future campaigns, you can repeat the process.
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Send away

These best practices can help you create engaging subject lines that will interest and engage your readers, even though there are no guarantees.

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If you have a tool to suggest that wasn’t included here, please add it in the comments.

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Cover image by Joseph Kalinowski/Content Marketing Institute