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12 Best Practices for Email Subject Lines – Proven Tips & Tricks

Email marketing remains a powerful tool for businesses to connect with their audience.

However, your email marketing efforts are only as good as your ability to get recipients to open your emails.

This is where email subject lines come into play. In this comprehensive guide, we will delve into the best practices for email subject lines, providing you with proven tips and tricks to increase your email open rates and engagement.

Trust us, we’ve been in the email marketing business for more than 10 years now. We’ve tried and tested all of the known practices and narrowed them down to the best 12 for you.

But before we talk about them in detail, allow us to start from the basics…

What is an Email Subject Line?

An email subject line is a concise phrase or line of text that summarizes the content or purpose of an email. It serves as the first thing recipients see in their inboxes and plays a crucial role in capturing their attention. Think of it as the headline of a newspaper article – it should provide a glimpse of what’s inside and entice the reader to explore further.

In essence, the email subject line is your first opportunity to make a positive impression on your audience. It should be clear, compelling, and relevant to the content of the email. Effective subject lines can significantly impact open rates and the overall success of your email marketing campaigns.

What is an Email Preheader?

An email preheader, also known as a preview text or snippet, is the text that appears immediately after or below the email subject line in an inbox. While it’s not as prominent as the subject line, the preheader is valuable real estate for providing additional context or a teaser for the email’s content.

Preheaders offer a chance to elaborate on the subject line or provide more information to entice recipients to open the email. It’s a supplementary tool to reinforce the subject line’s message and convince the reader that the email is worth their time.

Strategically using the preheader can improve open rates and provide a seamless transition from the subject line to the email’s content.

Importance of Email Subject Lines

The subject line of an email is critically important for several reasons:

  • First Impression: It’s the first thing recipients see, and first impressions matter. A compelling subject line can pique curiosity and encourage recipients to open the email.
  • Open Rates: A well-crafted subject line directly impacts open rates. If the subject line fails to capture interest, the email may go unopened.
  • Content Relevance: The subject line sets expectations for what’s inside the email. It should accurately reflect the content to avoid disappointment or confusion.
  • Mobile Optimization: With mobile devices being the primary platform for checking emails, subject lines must be concise and engaging to fit smaller screens.
  • Competition: In a crowded inbox, your subject line must stand out to compete with other messages. It’s your chance to make your email shine.
  • Branding: Consistent and memorable subject lines can reinforce your brand identity and make your emails easily recognizable.

In summary, the subject line is your email’s initial point of contact with recipients, and its effectiveness can determine whether your message gets noticed and engaged with or ignored.

How to Tell if an Email Subject Line is Good?

A good email subject line possesses several key attributes:

  • Clarity: It should clearly convey the email’s purpose or main message.
  • Relevance: The subject line should be directly related to the email’s content to avoid misleading recipients.
  • Conciseness: Brevity is crucial, especially for mobile users. Aim for a length of 6 to 10 words.
  • Engagement: It should provoke interest, curiosity, or a sense of urgency that compels the recipient to open the email.
  • Personalization: Personalized subject lines that address recipients by name or reference their past interactions can be highly effective.
  • A/B Testing: Testing different subject lines can help identify what resonates best with your audience.
  • Avoiding Spam Triggers: Stay clear of spammy words, excessive punctuation, and excessive use of capital letters.
  • Mobile-Friendly: Ensure the subject line is legible and engaging on mobile devices.
  • Consistency: Maintain consistency in branding and messaging to build trust with your audience.

Crafting a good email subject line involves a balance of these elements, aligning with your email marketing goals and the preferences of your target audience. It’s an ongoing process of refinement and adaptation to maximize the impact of your email campaigns.

Now, let’s explore the best practices for creating compelling email subject lines.

Best Practices For Email Subject Lines - Infographic

Crafting Attention-Grabbing Subject Lines

1. Keep it Short and Sweet

When it comes to email subject lines, brevity is key. Short and sweet subject lines are more likely to capture your audience’s attention. In today’s fast-paced world, people tend to skim through their inboxes, so a concise subject line can make all the difference.

Imagine you’re sending an email promoting a flash sale on your online store. Instead of a lengthy subject line like, “Exclusive Limited-Time Offer on Our Online Store – Save 50% on Select Items Today” consider something shorter and more impactful: “Flash Sale: 50% Off Today Only!” This shorter subject line gets straight to the point and creates a sense of urgency.

Incorporating brevity into your subject lines, along with relevant keywords, will increase the chances of recipients opening your emails.

2. Use Personalization

Personalization is a powerful tool for making your email recipients feel valued and recognized. When you address your subscribers by their names or reference their past interactions with your brand, you create a sense of connection and relevance. This can significantly boost your email open rates.

Imagine you’re running an e-commerce website, and you want to announce a special offer to your loyal customers. Instead of a generic subject line like, “Special Offer Inside,” you could use personalization to make it more engaging: “John, Your Exclusive 20% Discount Awaits!

Personalization not only grabs the reader’s attention but also conveys that you’ve taken the time to cater to their individual needs or preferences.

To enhance the effectiveness of personalization, consider using email marketing software that allows you to automate personalization based on subscriber data. This way, you can send personalized emails to a large audience without manually inputting each recipient’s name.

3. Create a Sense of Urgency

Creating a sense of urgency in your email subject lines can prompt quick action from your recipients. People are more likely to open an email if they believe there’s a limited time or opportunity associated with it.

Imagine you’re promoting a webinar, and you want to encourage sign-ups. Instead of a generic subject line like, “Upcoming Webinar Announcement,” consider adding urgency: “Last Chance to Register for Our Exclusive Webinar!

This subject line communicates that the opportunity is time-sensitive, encouraging readers to take action immediately. It’s essential to use words like “last chance,” “limited time,” or “act now” to convey the urgency effectively.

Creating a sense of urgency through your subject lines not only boosts open rates but can also lead to higher conversion rates when readers feel compelled to take immediate action.

4. Ask a Question

Asking a question in your email subject line can be an effective way to pique curiosity and engage your audience. Questions naturally stimulate the reader’s mind and encourage them to open the email to find the answer.

Imagine you’re launching a survey to gather customer feedback. Instead of a straightforward subject line like, “Customer Feedback Survey,” consider a question: “How Can We Serve You Better? Take Our Quick Survey!

This subject line not only invites the recipient to participate but also hints at the value they’ll gain by providing feedback.

When incorporating questions into your subject lines, make sure they are relevant to the content of your email. This helps maintain trust with your audience, as the email content should deliver on the promise implied by the subject line.

Asking questions in your subject lines can be a great way to foster engagement and encourage recipients to interact with your emails.

5. Use Emojis Sparingly

Emojis can add a playful and visually appealing element to your email subject lines. However, it’s important to use them sparingly and ensure they are contextually relevant to your message. Overusing emojis can make your subject line appear unprofessional and cluttered.

Consider an email promoting a summer sale. Instead of a plain subject line like, “Summer Sale Starts Now,” you could use emojis to make it more eye-catching: “???? Summer Sale Alert: Save Big Today! ????”

In this example, the sun emojis reinforce the idea of summer, adding a cheerful touch to the subject line.

When using emojis, be mindful of your audience and industry. Some emojis may not be universally understood or appreciated. Stick to commonly recognized emojis that align with your message.

Using emojis sparingly can enhance the visual appeal of your subject lines and make them stand out in crowded inboxes.

Testing and Analytics

6. A/B Testing

A/B testing, also known as split testing, is a powerful method to optimize your email subject lines. It involves sending two versions of an email to different groups of recipients and comparing their performance to determine which subject line is more effective. This method allows you to make data-driven decisions about your email campaigns.

When conducting A/B tests for your email subject lines, start by selecting a specific element to test. This could include variations in wording, personalization, emojis, or the use of urgency. For example, if you’re uncertain whether personalization or urgency works better, you can create two versions of your subject line:

Version A: “Exclusive Offer Just for You!

Version B: “Last Chance: Exclusive Offer Ends Soon!

Send these versions to two separate groups of your subscribers, making sure the groups are similar in size and demographics. Monitor the open rates and click-through rates for each version. The subject line with the higher performance indicates the approach that resonates better with your audience.

Keep in mind that A/B testing requires consistency and patience. Run multiple tests over time to gather significant data and fine-tune your email subject lines continuously.

7. Open Rate Analysis

Analyzing open rates is a fundamental aspect of optimizing your email marketing strategy. Open rates indicate how many recipients have opened your emails, making it a key metric for measuring the effectiveness of your subject lines.

To conduct open rate analysis effectively, segment your email list and compare open rates among different groups. For instance, you might have one segment of new subscribers and another of long-time customers. Analyze which subject lines perform better with each segment, as their preferences and behaviors may differ.

For example, if you’re running a newsletter for your online publication, you can segment your list into “New Subscribers” and “Returning Readers.” Compare the open rates for different subject lines:

Subject Line A: “This Week’s Top Stories

Subject Line B: “Welcome to Our Newsletter: Get the Latest Stories!

By analyzing open rates for each segment, you can tailor your subject lines to the specific interests and expectations of your audience.

8. Click-Through Rate Analysis

Click-through rates (CTR) measure the percentage of recipients who not only open your email but also take action by clicking on links within the email. Analyzing CTR is crucial for understanding how effective your email content is at engaging your audience.

When conducting CTR analysis, consider the alignment between your subject lines and the email content. Are the subject lines accurately representing what readers will find inside the email?

Imagine you’re promoting a new e-book through an email campaign. The subject line reads: “Download Our Latest E-Book Now!” Analyze the CTR to see if recipients who opened the email actually clicked through to download the e-book.

To enhance CTR, make sure your subject lines create a clear and compelling connection to the content within the email. Incorporate call-to-action (CTA) keywords that encourage action, such as “download,” “explore,” or “learn more.”

By conducting a thorough click-through rate analysis, you can refine your subject lines and email content to better engage your audience and drive desired actions.

Remember that A/B testing, open rate analysis, and click-through rate analysis are ongoing processes. Regularly evaluate and adjust your subject lines based on the insights gained from these practices to continually improve your email marketing strategy.

Avoiding Common Mistakes

9. Avoid Spammy Words and Phrases

One of the most crucial aspects of effective email marketing is ensuring that your emails reach your subscribers’ inboxes rather than being flagged as spam. To achieve this, it’s essential to avoid using spammy words and phrases in your subject lines.

Spam filters are designed to detect and filter out emails that exhibit spam-like characteristics. These characteristics often include words and phrases that promise quick riches, questionable offers, or exaggerated claims.

To maintain the trust of both your subscribers and spam filters, avoid using words like “free,” “cash,” “guarantee,” “buy now,” and excessive exclamation points in your subject lines. Instead, focus on creating subject lines that convey value, relevance, and authenticity.

For instance, if you’re promoting a discount on your online store, rather than using a spammy subject line like, “Huge Cash Savings – Buy Now! Guaranteed!“, opt for a more genuine approach: “Exclusive 20% Discount on Your Favorite Products.

By using clear and authentic language, you not only reduce the risk of your emails being marked as spam but also build trust with your subscribers.

10. Avoid All Caps

Subject lines written in all capital letters are considered poor email etiquette and can be perceived as shouting. They can come across as aggressive or spammy, which may discourage recipients from opening your emails.

Instead of resorting to all caps for emphasis, consider alternative ways to make your subject lines stand out. This could include using punctuation, emojis, or carefully chosen words to convey your message effectively.

For instance, if you want to draw attention to a limited-time offer, avoid writing your subject line like this: “LAST CHANCE: 50% OFF TODAY ONLY!” Instead, use a more balanced approach: “Don’t Miss Out: 50% Off Ends Today!

By avoiding all caps and using a well-crafted subject line, you can convey your message effectively without alienating your audience.

11. Avoid Overusing Punctuation

While some punctuation marks can be used to great effect in subject lines, overusing them can make your emails appear unprofessional and cluttered. Excessive exclamation points, ellipses, or other special characters can be distracting and may deter recipients from opening your emails.

To strike the right balance, use punctuation marks sparingly and only when they add genuine value to your subject lines. For example, if you’re announcing a new product launch, instead of, “Exciting News!!! New Product…Out Now!!!“, consider a cleaner approach: “Introducing Our Latest Product Release.

Avoiding common mistakes in your subject lines is crucial for maintaining a positive sender reputation, delivering your messages successfully, and engaging your audience effectively. By following these guidelines, you can craft subject lines that are both compelling and respectful of your subscribers’ preferences.

Remember that email subject lines are the gateway to your email content, so it’s essential to make a positive first impression and encourage recipients to explore further.

Mobile Optimization

As the majority of email opens occur on mobile devices, optimizing your email subject lines for mobile is essential. Mobile users tend to scan their inboxes quickly, making it even more critical to capture their attention with concise and engaging subject lines.

When crafting subject lines, consider how they will appear on smaller screens. Test your subject lines on various mobile devices and email clients to ensure they remain compelling and legible.

Imagine you’re sending an email promoting your latest blog post about email marketing tips. Instead of a lengthy subject line that might get cut off on mobile screens, such as “Unlock the Secrets of Successful Email Marketing Strategies,” opt for a shorter, mobile-friendly version: “Email Marketing Success Tips.”

Additionally, ensure that your email content and call-to-action buttons are also mobile-responsive to provide a seamless experience for mobile users.

By prioritizing mobile optimization, you can adapt to the evolving email landscape and cater to the preferences of your mobile-savvy subscribers effectively.


Mastering the art of crafting compelling email subject lines is a journey that combines creativity, data analysis, and an understanding of your audience’s preferences. By following the best practices outlined in this guide, you’re well on your way to achieving higher email open rates, engagement, and ultimately, better results from your email marketing campaigns.

Remember that while these best practices offer valuable guidelines, email subject lines are not one-size-fits-all. Tailor your approaches to your unique audience, industry, and campaign objectives. Continuously test, analyze, and refine your subject lines to adapt to changing trends and preferences.

As you embark on your email marketing journey, always aim to provide value to your subscribers. Craft subject lines that resonate with your audience’s needs and interests, and deliver content that exceeds their expectations.

Building a strong email marketing strategy, backed by compelling subject lines, can be a game-changer for your business or organization.

If you have any questions or need further guidance on email subject lines or email marketing in general, feel free to reach out. Your journey to email marketing success begins now!

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