How the Length of a Subject Line can Affect Open Rates and Engagement?

Created On
August 31, 2023
How the Length of a Subject Line can Affect Open Rates and Engagement?

In this digital world of email marketing, everybody’s inboxes are flooded with emails looking for their attention. Email marketers must find ways to help their emails stand out in all the crowded inboxes. One of the effective and efficient ways is optimizing the subject lines of these marketing emails. After all, these subject lines are the first content that the recipients read. 

Therefore, this is the only thing that will decide whether the email gets open. The opening of email subject lines is the first step towards the success of the email marketing goals. In this article below, we will explore the strategies that can be used to help in drafting magical and exciting email subject lines to get higher email open rates. 

Understanding the Importance of Subject Line Optimization

The email subject line stands as the ultimate gatekeeper, wielding the power to either captivate or repel recipients with its concise message. Subject line optimization is akin to fine-tuning a musical instrument – a delicate art of immense significance. As the initial point of contact, the subject line shapes the recipient's perception and determines whether an email is granted the coveted status of "opened." With the digital landscape brimming with a torrent of messages, a well-optimized subject line emerges as the beacon that guides audiences through the chaos, demanding attention amidst the clutter. Its impact on open rates is undeniable, as studies reveal personalized subject lines can elevate these rates significantly. 

Yet, beyond statistics lies the essence of relevance – a properly optimized subject line showcases a deep understanding of the recipient's preferences, establishing a connection that transcends mere communication. In a world where trust is paramount, the subject line becomes the epitome of transparency, building credibility that resonates. As a catalyst for action, a strategically crafted subject line sparks curiosity and nudges recipients toward meaningful engagement. Adapting to the ever-evolving email landscape, subject line optimization remains an indispensable tool, a testament to the intricate dance between communication, psychology, and the digital age.

The Impact of Subject Lines on Email Open Rates

The impact of subject lines on email open rates is profound and pivotal in email marketing. Subject lines are the first and often the only element of an email that recipients see before deciding whether to open it or send it to the trash. Their significance can be summarized as follows:

  • Attention Grabber: A well-crafted subject line grabs the recipient's attention amidst emails flooding their inbox. It entices them to pause and consider your message.
  • Curiosity Provoker: Subject lines that arouse curiosity encourage recipients to open the email to satisfy their intrigue. They hint at valuable content within, compelling the recipient to explore further.
  • Relevance Indicator: A clear and relevant subject line effectively communicates the email's content and purpose. It sets expectations, ensuring that recipients open the email with a clear understanding of what to expect.
  • Personalization: Personalized subject lines, which include the recipient's name or tailored content, create a sense of connection and relevance, often resulting in higher open rates.
  • Brand Image: Consistently well-optimized subject lines reflect positively on your brand's professionalism and understanding of your audience's needs, enhancing trust and credibility.
  • Spam Avoidance: Subject lines that appear spammy, misleading, or overly promotional can lead to recipients marking your emails as spam, damaging your sender's reputation and deliverability.
  • Engagement Catalyst: High open rates are a precursor to engagement. Once an email is opened, it can convey its message, drive actions, and achieve its marketing goals.
  • Testing Ground: Subject lines provide an excellent A/B testing and experimentation arena. Marketers can fine-tune subject lines to discover what resonates best with their audience, ultimately improving open rates.
  • Mobile-Friendly: Given the prevalence of mobile email usage, subject lines must be optimized for small screens. A compelling subject line is succinct yet impactful, ensuring it's evident and enticing on mobile devices.
  • Metrics Benchmark: Open rates are a fundamental metric in email marketing, and subject lines are pivotal in determining this metric's success. They set the stage for the entire campaign's performance.

Best Practices for Optimization of Email Subject Lines to get Higher Open Rates

Optimizing the length of your email subject lines is crucial for achieving better open rates and engagement. However, there's no one-size-fits-all formula, as it largely depends on your audience, content, and goals. Here are some best practices to consider when crafting subject lines of varying lengths:

For Short Subject Lines (Under 50 Characters):

  • Keep it short and to the point. Communicate the email's main message or offer concisely.
  • Place the most crucial information at the beginning of the subject line to ensure it's seen, especially on mobile devices.
  • Use brevity to spark curiosity. Leave enough unsaid to pique the recipient's interest and make them want to open the email.
  • Incorporate actionable words or phrases encouraging recipients to take immediate action, like "Limited Time Offer" or "Last Chance."
  • Emojis can help convey emotions or ideas succinctly. Use them sparingly and relevantly to enhance your subject lines.

For Medium-Length Subject Lines (50-70 Characters):

  • You have more room here, so balance clarity with intrigue. Provide enough information to convey your message while maintaining curiosity.
  • If possible, incorporate personalization elements like the recipient's name or location to make the subject line more engaging.
  • Make every word count. Avoid unnecessary filler words or phrases that don't add value to the subject line.
  • Use questions or punctuation to create a sense of curiosity or urgency. For example, "Ready for a Summer Adventure?" or "Don't Miss Out!"

For Longer Subject Lines (70+ Characters):

  • Longer subject lines can provide more context and detail. Use this space to set expectations about the content inside the email.
  • Craft a subject line that tells a brief story or paints a vivid picture. Storytelling can draw recipients in and create emotional engagement.
  • Utilize personalization extensively in longer subject lines to make them feel tailored to the recipient's interests or needs.
  • If applicable, include relevant keywords or phrases that can improve the email's search engine optimization (SEO) value.
  • While longer subject lines offer more space, avoid overcrowding them with too much information. They should still be scannable and digestible.

General Best Practices:

  • Continuously A/B test subject lines of varying lengths to determine what works best for your specific audience and content.
  • Segment your email list based on recipient preferences and behavior. Tailor subject line length to different segments if necessary.
  • Ensure that your subject lines are mobile-friendly, regardless of their length. Long subject lines should still be displayed effectively on smaller screens.
  • Your subject line should always convey a clear value proposition regardless of length. Recipients should know what's in it if they open the email.
  • While you want to create curiosity, avoid misleading or clickbait subject lines. Trust is crucial in email marketing.
  • Regularly analyze open rates and engagement metrics to refine your subject line strategies.

What are the Methods for Creating Email Subject Lines that Increase the Open Rates?

Creating email subject lines that increase open rates is crucial to successful email marketing. Here are some effective methods and strategies to follow:

  • Personalization: Incorporate the recipient's name or other personalized elements in the subject line. Personalization makes the email feel more relevant and tailored to the individual.
  • Segmentation: Segment your email list based on recipient behavior, demographics, or preferences. Craft subject lines that specifically target each segment, increasing the chances of relevance.
  • Use Clear and Concise Language: Be clear about the email's content or offer. Avoid jargon or ambiguity. A straightforward subject line helps recipients understand what they'll get by opening the email.
  • Create Curiosity: Use intriguing or thought-provoking language to spark curiosity. Give recipients a reason to open the email to satisfy their interest.
  • Leverage Urgency and FOMO: Communicate a sense of urgency or fear of missing out (FOMO) in your subject lines. For example, "Limited Time Offer" or "Last Chance to Save."
  • Ask Questions: Pose a question in your subject line that the email content answers. Questions can engage recipients and prompt them to open the email for a reply.
  • Highlight Benefits: Clearly state the benefits or value the recipient will gain by opening the email. Explain what's in it for them.
  • Keep It Short: Short subject lines often perform well, especially on mobile devices. Aim for brevity while still conveying your message effectively.
  • A/B Testing: Continuously test different subject lines to determine which resonates best with your audience. A/B testing can help refine your approach over time.
  • Avoid Spammy Language: Clear words and phrases commonly associated with spam, such as "free," "money," or excessive use of exclamation marks.
  • Use Emojis Sparingly: Emojis can add visual appeal to subject lines and convey emotions, but use them sparingly and only when relevant to your content.
  • Personal Subject Lines: Share personal stories or anecdotes about your email content. This can create a sense of connection and authenticity.
  • Numbers and Lists: Include numbers or create list-based subject lines. For example, "Top 10 Tips for..." or "5 Ways to..."
  • Mobile Optimization: Ensure that your subject lines are concise and make sense when viewed on mobile devices, as a significant portion of email opens occurs on smartphones.


The length of a subject line in your email marketing campaigns can significantly affect open rates and engagement. There's no one-size-fits-all answer, as the ideal size depends on various factors, including your audience, email type, and content. The key is to balance clarity and curiosity, conciseness and context.

In the ever-evolving email marketing landscape, subject line optimization remains vital. Understanding how the length of a subject line can impact open rates and engagement is just one piece of the puzzle. To excel in email marketing, marketers must stay attuned to their audience's preferences, continuously experiment, and adapt their strategies to remain effective in a dynamic digital world.

What’s a Rich Text element?

The rich text element allows you to create and format headings, paragraphs, blockquotes, images, and video all in one place instead of having to add and format them individually. Just double-click and easily create content.

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A rich text element can be used with static or dynamic content. For static content, just drop it into any page and begin editing. For dynamic content, add a rich text field to any collection and then connect a rich text element to that field in the settings panel. Voila!

How to customize formatting for each rich text

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Author’s Details

Tanmay Shukla

Tanmay is a SEO Content Writer at Smartlead. His zeal and enthusiasm in writing led him to the path of being a Content Writer. He has been advancing in this field by possessing more knowledge and skills. His constant endeavor has made him a whiz in SEO, Creative Writing, and driving sales through writing.


Edited by:

Charu Mitra Dubey


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