How to Write Powerful Email Subject Lines

Your email subject line is more than just a headline—it’s a first impression. It’s the digital equivalent of meeting someone’s eyes and offering a handshake. With just a few words, you either invite readers in or risk turning them away.

In the realm of email marketing and personal communication alike, the subject line holds significant weight. It can be the deciding factor that influences whether your message is read or ignored, impacting your email open rates and the overall success of your email campaigns.

So, let’s explore best practices, psychological triggers, and practical tools that will empower you to write subject lines that captivate your audience and sidestep the dreaded spam folder.

Table of Contents

Importance of Email Subject Lines

The subject line is the first thing people see when you’re sending an email. And whether you’re a large corporation or a small business, that’s a big deal. Your email’s first impression can affect whether or not people open it and see your message. Knowing how to write a good email subject line can significantly boost your email open rates. This means more people will likely interact with your email campaign and purchase your products or services.

In short, a strong subject line is the key to successful email marketing.

Understanding Email Open Rates

Email open rates tell us how many people clicked to open your email. Open rates let you gauge how effective your email campaign is. The better your subject line, the higher the open rates can be.

Click-through rates (CTR) measure how many clicks your links within the email receive compared to how many times the email was opened. This can help you understand how successful your messaging within the email is for creating conversions.

Knowing the average open rate in your industry helps you understand what to aim for. If you’re below average, you know you need to improve your email’s subject lines and other aspects to get people to open and click.

Remember that many customers are likelier to open emails from email addresses they recognize. This is why one of my top email marketing tips is to create permission-based campaigns.

Principles of Effective Email Subject Lines

So, how do you write a good email subject line that people will click on? While there’s no secret trick, you can follow a few fundamental principles.

When writing your email subject line, consider using:


People don’t have time to read a long-winded subject line. Keep it short and to the point. A good rule of thumb is to aim for 50-60 characters.


Be clear about what your email is about. Vague subject lines could make people skip your email, negatively affecting your open rates.


Your subject line should be relevant to your audience. The email’s content and the subject line must be aligned. This can make the difference between someone opening your email or ignoring it.


Many people love seeing their names or something personal in a subject line.

Creating a Sense of Urgency

This is a marketing tip that works for many types of advertising. In email marketing, it often yields higher open rates. Phrases like “limited time offer” or “last chance” can create a sense of urgency that nudges people to open and click.

Tools for Crafting Email Subject Lines

You won’t write perfect marketing email subject lines after reading a single blog post. But as you dive into your email campaigns, you can learn as you go by testing your subject lines.

Many methods and online tools exist to help you test your subject lines. Some of the most popular ways of testing your subject lines include:

Subject Line Testers

These tools evaluate your subject lines based on algorithms and give you a score. They can also provide helpful feedback on why your subject line does or doesn’t pass the test, such as grading its length, wording, and other criteria.

A/B Testing

Also known as split testing, this method involves sending two different subject lines to a small part of your audience to see which performs better. Then, you can check the data gathered by your email campaign software to determine which email subject lines get more opens. This is a popular method for determining which subject lines work best when preparing for a campaign.

Analytics Tools for Monitoring Open and Click Rates

Analytics tools are essential for gauging the success of your email campaigns. These tools provide real-time data on open and click rates, allowing you to adjust your strategy as needed. Features like audience segmentation further refine your data, helping you understand which subject lines work for different segments of your audience. In short, analytics tools offer the insights you need to optimize your email marketing efforts.

I personally love the analytics tools that come with ActiveCampaign.

Types of Email Subject Lines That Get Opened

Various styles of subject lines can attract your reader’s attention. There is a wide variety of types of subject lines to choose from. The type you choose depends on the specifics of your campaign, such as audience, tone, and goals.

Here are some of the most popular types of subject lines, with a few examples of each:

Question-based Subject Lines

Asking a question can spark curiosity and invite the reader to open the email for the answer.

  1. “Is Your Marketing Working?”
  2. “Need a Vacation?”
  3. “How Happy Are You With Your Current Job?”


A little mystery can go a long way. Teasers like “You won’t believe what happened next” can get people to click to satisfy their curiosity.

  1. “Unlock Your Potential Today”
  2. “The Secret Ingredient You’ve Been Missing”
  3. “You Won’t Believe What’s Inside!”


“How to” subject lines offer a promise: open the email, and you’ll learn something new. For example, “How to write a good email subject line” could be a strong choice for promoting this blog!

  1. “How to Increase Your Sales in 30 Days”
  2. “How to Write Emails People Will Actually Read”
  3. “How to Nail Your Next Interview”


Numbers in the subject line, such as “5 ways to improve your marketing,” can catch the eye and promise easily digestible content.

  1. “Top 5 Marketing Tips You Need”
  2. “7 Hacks for a Better Morning Routine”
  3. “10 Books You Must Read This Year”

Personal Emails

In personal emails, using the recipient’s name or referring to a past interaction can make the subject line feel more personal and relevant.

  1. “John, Your Custom Report is Ready”
  2. “We Miss You, Sarah! Special Deal Inside”
  3. “Mike, Remember This from Last Summer?”

The Psychology of Persuasive Subject Lines

Understanding the psychology behind persuasive email subject lines can give your email campaigns a significant edge. By tapping into inherent human behaviors and triggers, you can craft subject lines that resonate emotionally, compelling recipients to open your email.

Here are some common psychological triggers marketers use when creating powerful email subject lines:

Triggering Curiosity

Curiosity is a powerful psychological force that drives people to seek and acquire new information. By crafting subject lines that pique curiosity, you tap into a natural human desire for knowledge and understanding. When triggered, curiosity creates a form of cognitive dissonance that the reader feels compelled to resolve, often leading to higher open rates.

FOMO (Fear Of Missing Out)

FOMO is rooted in the psychological theory of loss aversion, which posits that people are more motivated to avoid loss than to attain gain. By indicating that a unique opportunity or reward is in danger of being missed, you create a sense of urgency. This pressure to act quickly plays on human psychology’s inherent desire not to miss out on something valuable.

Addressing Pain Points

Pain points evoke a psychological response because they touch on challenges or issues that the reader is experiencing. Addressing these directly in your subject lines speaks to their current state of need, encouraging them to seek relief or solutions. Doing so can generate immediate interest and an emotional connection, increasing the likelihood that your email will be opened.

Best Practices to Avoid the Spam Folder

We’ve all experienced it: carefully crafted emails that end up in the recipient’s spam folder, never to be seen again. If you want your emails to achieve higher open rates, it’s crucial to understand how to bypass this email purgatory.

So, what steps can you take to ensure your emails land in the inbox?

Words to Avoid

Some words are red flags for email service providers and can land your email in the spam folder. Words like “free,” “win,” and “exclusive offer” often trigger spam filters. By avoiding these and other suspicious terms, you can improve the chances of your email being seen.

The Role of Domain Reputation

Your domain’s reputation is vital for determining whether your email will end up in the spam folder. If your email server has been used for sending out spam or malicious content in the past, there’s a higher likelihood that spam filters will flag your subsequent emails—regardless of how well-crafted your subject lines are.

Maintaining a healthy domain reputation is essential. You can do so by consistently sending out high-quality, relevant content to a list of subscribers who have willingly provided their email addresses. Monitoring your domain’s reputation and taking steps to improve it can significantly enhance the deliverability of your emails, making sure they reach the inbox rather than the dreaded spam folder.

Avoid Excessive Punctuation or Capital Letters

Spam filters also look for subject lines that are trying too hard to get attention. Using ALL CAPS or multiple exclamation points can make your email look like spam, even if it isn’t. Keeping it simple and professional is usually the best approach.

Common Mistakes and How to Avoid Them

Every marketer makes mistakes. The important part is that we learn from them! If you’re wondering how to write a good email subject line, avoiding common pitfalls is half the battle.

Some of the most common mistakes marketers make when writing a subject line include:

Being Too Vague

Vague subject lines don’t give your audience any reason to open your email. Subject lines like “Update” or “News” are too generic and don’t convey value. Instead, make it specific. Let your audience know what’s in it for them right in the subject line.


While making grand promises in your subject line to get that click is tempting, overhyping can backfire. If your email doesn’t deliver on the promise, your audience will likely lose trust in your emails, leading to lower open and click rates in future campaigns.

Ignoring the Mobile Experience

Over half of all emails are opened on mobile devices, so it’s crucial that your subject lines look good and make sense on smaller screens. Test subject lines to ensure they don’t get cut off and convey the message in fewer words, as mobile screen real estate is limited.

Underestimating the Power of Preview Text

The preview text is the small snippet that appears alongside your email subject line. Unfortunately, it often gets neglected by marketers. Think of it as an extension of your subject line; it should offer a compelling reason to open the email or provide additional context that your subject line couldn’t cover. Failing to optimize this could mean missed opportunities for higher open rates.

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