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Mastering the Art of Newsletter Subject Lines: Six Tips to Boost Open Rates

Mastering the Art of Newsletter Subject Lines: Six Tips to Boost Open Rates

If you think about the promotional emails and newsletters in your inbox, they probably seem like a lot of noise. However, email marketing is still one of the most effective ways to generate traffic and turn casual readers into loyal customers. In fact, one study found that for every $1 spent on email marketing, you can expect an average return of $40, which is higher than other digital marketing channels like search and social.

It makes sense, too. If you think about it, most people check their email once a day at a minimum. However, lots of people are active across email throughout the entire workday, and many users check email even earlier than that. Data from OptinMonster shows that more than half of users check their email before doing anything else online for the day.


Email provides plenty of opportunities to catch your reader’s eye. With dwindling attention spans and plenty of content competition, your email subject line needs to be perfect — a task that’s both an art and a science.

Here are six tips to write subject lines that stand out amongst the crowd and will compel your readers to open up and engage with your content.

1. Keep It Short and Sweet

As you know, it can be hard to grab a reader’s attention when there’s plenty of other content they could consume in their inbox alone. That’s why brevity is important for subject lines, and ideally they should be 30–50 characters total. Not only does this optimize for short attention spans, but it also ensures that your subject line is not cut off in the email preview so that readers can see the full impact of your message.

Example of a short and concise subject line.

2. Use Language That Inspires Action

Words that prompt action from your reader can boost your open rates. When crafting your subject line, try to use verbs that create a sense of urgency. According to HubSpot, emails that use urgent language like “breaking,” “important,” or “alert” have higher open rates

Example of subject line that uses actionable language.

3. Personalize When Possible

Personalization can make your audience feel valued and can quickly grab their attention. Campaign Monitor found that readers are 26% more likely to open emails with a personalized subject line. When possible, including the person’s first name and other details can make the email feel like it was customized just for them

A little personalization can go a long way when crafting email subject lines.

4. Use Numbers

Making use of numbers can make your subject line appear more eye-popping and specific. Clear and digestible information will give the reader a better idea of the email’s objective. A/B testing by Campaign Monitor found that numbers in subject lines resulted in 57% better open rates.

Numbers are a great way to make your subject line pop.

5. Be Clear and Specific

It’s always important to stay away from any sort of vague or mysterious language in your subject lines, and instead try to clearly communicate what readers can expect from your email. This will also build trust with your audience so they never feel like they were tricked into opening an email.

It helps to clearly convey the content of your email.

6. A/B Subject Lines

The best way to know if your email subject lines are resonating with your audience is through A/B tests. With each email sent, conduct A/B tests to compare which types of subject lines perform the best across your readers. Pay attention to open rates, click-through rates, and any other engagement metrics to see what performs well. It’s best to review this data after every send and refine your subject line strategy as you go.

How A/B testing works. From Zapier.

Make Newsletters a Part of Your Publishing Process

Creating effective subject lines takes creativity, precision, and experimentation. Since the subject line is your elevator pitch to your content, it’s important to prioritize it with each email you send. But that can be hard with the full plate already in front of content creators who are always trying to stand out from the competition.

RebelMouse is an AI-enabled CMS that’s also a powerful platform for optimizing newsletters. Our integration with major email service providers like Mailchimp and Sailthru include A/B testing, automation, responsive design, content curation, and tools to seamlessly weave your email strategy into your publishing process.

Easily schedule newsletters in RebelMouse’s editing interface.

Ready to up your email newsletter strategy with perfect subject lines? Request a demo and let’s start working together.

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