How To Write Subject Lines That Increase Open Rates

Most email clients truncate subject lines after a certain number of characters, typically between 40 and 60 characters on mobile devices. If your subject line is too long, the most important information might be hidden when the subscriber views it on their phone. You should aim to place the most compelling hook at the very beginning of the string. Keep in mind that users often look for a clear reason to open the email, such as a solution to a problem or an answer to a question. If you put your brand name or a generic label at the front, you waste valuable space that could be used for a call to action or a value proposition.

When writing for different segments, consider the intent of the recipient. A subscriber who just signed up for a newsletter expects a welcome message, so the subject line should be direct and confirm their action. Conversely, a subscriber who has been inactive for months requires a different approach, perhaps highlighting a specific update or an offer designed to re-engage them. In a typical account managed through a CRM, segmenting these audiences allows you to tailor the tone, ensuring that the subject line feels relevant to the specific stage of the customer journey.

Many marketers fall into the trap of using overly clever or mysterious subject lines, hoping to pique curiosity. While this can work occasionally, it often fails to build long-term trust with your audience. If a reader feels tricked into opening an email because the subject line did not match the actual content, they are less likely to open future messages. Reliability is the foundation of a healthy email list. Your subscribers should know exactly what they are getting when they see your brand in their inbox, which builds a pattern of predictable engagement over time.

Consistency also applies to your brand voice. If your marketing emails are typically professional and informative, a sudden shift to all-caps or excessive emojis can appear jarring or even like a security threat. Maintain a steady cadence in how you present your subject lines. This does not mean you cannot be creative, but your creativity should support the message rather than distract from it. A clear, honest subject line that highlights a specific benefit will consistently outperform a cryptic one in the long run.

To drive action, your subject line must create a sense of relevance or urgency that matters to the reader. Focus on the ‘what is in it for them’ aspect of your communication. Instead of focusing on your product features, focus on the result the user will achieve after reading your email. This shift in perspective makes your subject line much more appealing to the target audience. You can use various techniques to improve your open rates while maintaining a professional standard for your brand.

• Use active verbs to encourage the reader to take a specific step immediately.
• Highlight a specific benefit or solution to a known pain point your audience faces.
• Reference a recent interaction they had with your website or service to increase relevance.
• Ask a relevant question that the reader can answer by opening the email.
• Keep the language simple and avoid industry jargon that might confuse the recipient.

A/B testing is the most reliable way to determine what works for your specific audience. By creating two variations of a subject line and sending them to a small percentage of your list, you can observe which version generates more opens. Most modern CRM platforms offer built-in tools for this process. You can set the test to run for a few hours before the platform automatically sends the winning version to the remainder of your subscribers. This data-driven approach removes the guesswork from your email strategy.

When setting up these tests, change only one element at a time. If you change both the tone and the length, you will not know which factor contributed to the result. For instance, compare a question-based subject line against a statement-based one. Keep the rest of the email content identical. Over time, you will build a library of successful patterns that you can apply to future campaigns, helping you refine your outreach without relying on assumptions.

• Avoid using excessive punctuation like multiple exclamation marks, which can make your email look like spam.
• Do not use misleading subject lines that have no relation to the actual body content.
• Avoid over-relying on clickbait tactics that promise results you cannot deliver.
• Do not ignore the preview text, as it acts as a secondary subject line that can increase open rates.
• Avoid long, complex sentences that are difficult to scan quickly on small screens.

The preview text, often called the preheader, is the snippet of text that appears next to or below your subject line in many email applications. It is an often-overlooked space that can significantly influence whether someone opens your email. Many people write a great subject line but neglect the preview text, allowing the email platform to pull in the first few words of the body, which might be ‘view in browser’ or ‘load images’. You should treat this space as an extension of your subject line.

Use the preview text to provide additional context or a secondary hook. If your subject line is a question, the preview text can provide a hint about the answer. If the subject line announces a sale, the preview text can specify the discount percentage or the duration of the offer. By coordinating these two elements, you provide a more complete message before the user even opens the email, which helps in setting expectations and increasing the quality of your open rate.