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Subject Lines That Sell: Unlock the Secret to Cold Email Success!

Unlock the Secret to Cold Email Success

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Effective subject lines are the linchpin of successful cold email campaigns, with 64% of recipients opening emails solely based on this factor. 

However, you must learn top writing strategies to create converting subject lines. These include psychological tactics, personalization, rigorous testing of email elements, and more.

This guide captures all this information. So, let us begin our exploration.

6 Tips to Create Converting Cold Email Subject Lines

Here are the six best ways to grab your prospects' attention via cold email subject lines:

1.  Apply Psychological Triggers and Curiosity Elements

Emotional or psychological content is 94% more effective compared to rational ones. 

Thus, when crafting your subject lines, consider how you can tap into your prospect's curiosity and pique their trust and interest. One way to apply these psychological triggers is to use powerful words and phrases. 

These can work wonders here. For example, using terms like "Exclusive Invitation" or "Secret Strategy Revealed" can trigger curiosity and prompt them to open your email to learn more. 

Check out the below list of best power words to: 


By incorporating these elements, you're offering information and enticing them with the promise of something valuable they might miss out on.

Here are some examples of attention-grabbing subject lines incorporating the power words provided:

  • "Unlock Astonishing Secrets to Skyrocket Your Sales"
  • "Banned Techniques That Will Transform Your Marketing Strategy"
  • "Crazy Savings Await: Don't Miss Out on Exclusive Offers"
  • "Key Strategies for Dominating Your Market Revealed"
  • "Private Invitation: Discover Insider Tips for Success"
  • "Unique Opportunity: Be the First to Try Our Revolutionary Product"
  • "Secret Tactics Top CEOs Use to Stay Ahead of the Competition"

2. Add Personalization Within Subject Lines

How can you make your cold emails stand out in crowded inboxes? By addressing your prospect with a personal touch. It includes: 

  • Using prospects' name
  • Mentioning relevant details about their company or industry
  • Including social proof, such as mentioning a mutual connection or a well-known client

The above elements add credibility and familiarity, making your email more appealing to the recipient. It shows you've done your homework and aren't just sending a generic message. In fact, personalizing subject lines can boost open rates by a massive 50%.

3. Take a Data-Driven Approach to Subject Line Creation

When crafting your cold email subject lines, you must base your decisions on data insights. Analyze past performance data and audience segmentation. Look into which subject lines have historically generated higher open rates or engagement levels. It'll let you tailor subject lines to resonate better with specific segments of your target audience. 

You can use tools like Send Check It, SubjectLine, and ZURB to effectively gather and analyze this data. By leveraging data-driven insights, you can optimize your subject lines to maximize their effectiveness and increase the chances of conversion.

4. Pay Attention to Email Snippets

Take a glance at the grey-colored text next to the subject line, representing the email snippet:


Neglecting the preheader text space will result in your email appearing like this:


These snippets are what your recipients see alongside the subject line in their inbox. As evident, they enhance the subject line by giving readers a glimpse into the email's content. They can significantly impact a prospect's first impression. 

Ensure your email snippet complements your subject line and entices readers to open your email. Here are the best practices to follow:

  • Keep it concise (30 to 80 characters)
  • Ensure it differs from the subject line.
  • Provide clear action to the readers.
  • Entice with an appealing incentive.
  • Utilize the preheader as a summary of the email.
  • Test the preheader's appearance across various devices.

This way you can craft a compelling teaser encouraging recipients to click through.

5. A/B Test to Optimize Subject Line 

When crafting your cold email subject lines, it's vital to A/B test different variations to determine the most effective ones. You can experiment with wording, length, tone, and punctuation. 

Analyzing open rates and other relevant metrics can help you identify which subject lines resonate best with your audience. This iterative approach allows you to refine your subject lines continuously for maximum impact and conversion.

6. Maintain Compliance and Best Practices

Ensuring your subject lines comply with regulations such as the CAN-SPAM Act and GDPR is essential. It means avoiding deceptive or misleading subject lines and clearly indicating the email's content. While being attention-grabbing is crucial, it's equally important to maintain professionalism and integrity. 

Best practices include:

  • Using personalized subject lines.
  • Avoiding spammy language or excessive punctuation.
  • Providing value to the recipient.

Adhering to these guidelines can build trust with your audience and increase the likelihood of your emails being opened and converted.

Avoid Common Subject Line Pitfalls and Spam Triggers

You can try your best and follow the above tips to create impactful subject lines. Yet, you may unknowingly do things that can blunder the whole outcome. So, here are some common mistakes and triggers of email spam you must consider: 

Check out the common subject line pitfalls:

  • Vague or ambiguous subject lines that fail to convey the email's purpose.
  • Overly lengthy subject lines that may get cut off in email previews.
  • All caps or excessive punctuation can come across as aggressive or spammy.
  • The lack of personalization makes the email seem generic and impersonal.
  • Subject lines that contain spelling or grammar errors undermining professionalism.
  • Subject lines that are too sale-sy or promotional lead to a higher likelihood of being marked as spam.

Here are spam triggers you must avoid:

  • Words or phrases commonly associated with scams or fraudulent activities (e.g., "free," "limited time," "urgent").
  • Excessive exclamation marks or symbols (e.g., "$$$!!!").
  • Words related to adult content or explicit material.
  • All caps in the subject line.
  • Phrases like "act now" or "buy now."
  • Promises of unrealistic benefits or outcomes (e.g., "lose weight fast," "get rich quick").
  • Trigger words related to financial services, such as "credit," "loan," or "investment."
  • Words commonly associated with phishing attempts, such as "password," "account," or "verify."


Apply these above tactics to crafting compelling subject lines for your targeted cold emails. And drive engagement and conversions. By implementing data-driven approaches and experimenting with optimization, you can unlock the interest of your prospects. Remember, innovation and adaptation are key to staying ahead in the ever-evolving landscape of email outreach.

Let Revnew, the renowned B2B lead generation agency, help you out. Our experts have the experience and specialization in creating and converting cold email campaigns. Contact us here to learn more.

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