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160+ Cold Email Subject Lines With Proven Open Rates [Real Data]

This post was written by: Sierra Skelly

Sierra Skelly • Senior Content Marketing Specialist

Last Updated: Nov 29, 2023

Don’t scare off potential prospects with boring email subject lines.

You may feel like the body of your email is the meat and potatoes (AKA, the most important part). And while the content of your email is essential, don’t underestimate the importance of the subject line — it plays a crucial role in ensuring the recipient actually reads the email. 

Those who spend most of their time sending emails know that writing a creative cold email subject line that gets opened is no walk in the park.

Sending carefully crafted subject lines is how we promote the content we create and as a result, build links for our clients. Just look at how we built 1,500+ links for a fintech client — all through cold email outreach and digital PR.

To uncover what makes a subject line clickable, we analyzed 100 email campaigns with over 10,000 emails sent to discover what makes a successful cold email subject line.

Table of contents:

How to Write Good Cold Email Subject Lines

The best cold email subject lines are relevant, thought-provoking, and emotional. They use the AIDA (Attention, Interest, Desire, Action) formula to intrigue prospects and entice them to open the email.

At Siege, we follow a general formula for our email subject lines and listed it below:

Cold email subject line formula.

The first part of the formula is clearly stating what you’re promoting or asking for. For example, if you’re reaching out to schedule a meeting, your email subject line would look like this: “Meeting for Kiera: Influencer marketing strategy.” 

Example timely cold email subject line.

Then, you’ll want to summarize what you’re offering in a thought-provoking yet concise manner. Are you launching a new copywriting service? Promoting your new product? Summarize your product or service in seven words or less.

For example, if you’re launching a new inventory management software that aids in preventing employee theft, your subject line could look something like this: “Resource for Trish: How to prevent employee theft.”

Example cold email subject line template.

While this is a sales email subject line, it doesn’t feel like one right away. Instead, it simply feels like you’re sharing a resource targeting a pain point many business owners face. Prospects are more likely to open an email with a good subject line that feels more conversational than salesy.

Email Subject Lines That Get Opened

Every email you send should have a carefully crafted subject line that is made relevant to the specific person or site you’re reaching out to. As a rule of thumb, we keep our email subject lines under 50 characters for best results. Any longer, and you run the risk of your subject line being cut off. 

While the type of cold emails we send may be different from your needs, there are some core themes you can apply to your project. Read on for over 160 successful subject line examples.

Personalized Subject Lines 

The worst kinds of subject lines are the ones that feel automated. You want the prospect to think you’re a living, breathing human — not a bot.

The easiest way to do this is to use the prospect’s name. When sifting through a full email box, somebody is more likely to stop on subject lines that include their name. Use their company or product name if you can’t find theirs. If you have a mutual connection with your prospect, include that as well.

The next way to personalize your subject line is to play into your prospect’s ego. Did they just publish a book or launch a new website? Did they write a blog post you found interesting? Mention these in your subject line. It will make them feel important, and they’ll appreciate that you did your research beforehand.

Example personalized cold email subject line.

Here are some examples of personalized email subject lines:

  1. Congratulations on [Event Name]!
  2. [First Name], do you have 5 mins?
  3. [First Name], here’s how you can crush Q3 goals
  4. Reaching out to a fellow [University] alumni
  5. [First Name], have you been taking care of your mental health?
  6. [First Name], I have a question about your recent article
  7. [Mutual Connection] recommended we connect, [First Name]
  8. Hi [First Name], can I help with [Prospect’s Industry]?
  9. [First Name], a solution to your [Prospect’s Pain Point]
  10. [First Name], I have an idea to boost [Prospect’s Interest]
  11. [First Name], let’s amplify [Prospect’s Company] in 10 minutes
  12. [Referral Name] referred me to you, [First Name]
  13. We share [insert common interest], [First Name]!
  14. So nice to meet you, [First Name] – let’s connect.
  15. Feeling overwhelmed, [First Name]? Let me assist you.
  16. Hoping to collaborate with [First Name] on [their goal]
  17. [First Name], let’s discuss your recent article.
  18. [First Name], ready to dive into [topic]?
  19. [First Name], a thought on your recent article
  20. [First Name], let’s conquer those Q1 milestones!
  21. [First Name], elevate your [specific goal] with us.
  22. [First Name], time for a [topic] discussion.
  23. [First Name], a quick request about [their recent activity].
  24. [First Name], a [benefit] tailored for [Their Company Name].
  25. [First Name], ready for a [topic] conversation?
  26. Helping [prospect’s company type] with [common issue] — could your company benefit, [First Name]?
  27. Say goodbye to [pain point], [First Name]

Subject Lines That Ask Questions

A great way to entice a prospect to open your email is to ask them a thought-provoking question. Not only should your question make the reader think, but it should also be relevant and pique their interest.

For example, if you’re pitching a business you know has started using AI, consider asking them how it’s going. Not only is this question timely, but it hits a pain point for many business owners right now: How to implement AI into business. Once they open your email, let them know how your product or service can help.

Example cold email subject line question.

Here are some great question subject line examples in action:

  1. Are you financially responsible for a pet?
  2. Is it time to open a new business location?
  3. Can you afford to move out?
  4. How safe is your neighborhood?
  5. Have you heard about [subject]?
  6. Thoughts on [subject]?
  7. 10 minutes next week?
  8. Should you monitor your remote employees?
  9. Have you been feeling [emotion]?
  10. Can you meet on [Day]?
  11. Is your ego sabotaging your small business?
  12. Should your business accept cryptocurrency?
  13. What do your dreams mean?
  14. Is it time to scale your business?
  15. How much should entrepreneurs pay themselves?
  16. Are you using AI in your business?
  17. Have you considered investing in sustainability?
  18. Is your social media strategy yielding results?
  19. How’s your team’s morale these days?
  20. Is your website optimized for mobile users?
  21. What’s your plan for the upcoming holiday season?
  22. Is your cybersecurity up to date?
  23. Are you keeping up with industry trends?
  24. Are you leveraging data analytics for growth?
  25. How do you handle customer feedback?
  26. Are you satisfied with your current software?
  27. What’s your strategy for customer retention?

Attention-Grabbing Subject Lines

It doesn’t matter how great your email or sales pitch is if no one opens it. Creating a subject line that grabs your prospect’s attention is a great way to get your email opened and read. An attention-grabbing subject line typically includes something shocking, controversial, or compelling. 

Just like you would the title of a book or movie, make your subject line compelling enough that someone has to do a double take. A great way to do this is by evoking an emotion or debunking a common belief. For example, if you’re promoting your new service, get your foot in the door with a subject line that includes impressive statistics from your launch. 

You can do this in a few ways:

  • Refute a common belief.
  • Share the shocking results of a study.
  • Evoke an emotion.
  • Make your email feel “exclusive.”
  • Include impressive statistics.

Example attention-grabbing cold email subject line.

Here are some examples of attention-grabbing subject lines:

  1. Science-backed benefits of napping at work
  2. Self-care isn’t just for Sunday
  3. Study: Your steering wheel is 4X dirtier than a public toilet seat
  4. +[XX]% in revenue for businesses that add this to their site
  5. EXCLUSIVE: You’ve been invited to…
  6. Did you hear what happened?
  7. Only X weeks left to achieve [goal]
  8. Breaking down the myths of [topic]
  9. Maximize your [specific metric] with these tips
  10. The missing piece to your [challenge]
  11. New horizons in [industry] – stay informed
  12. Unlock the potential of [new tool/technology]
  13. A fresh perspective on [common challenge]
  14. Mastering [specific skill] in no time
  15. The roadmap to achieving [specific goal]
  16. Your invitation to the ultimate [event]
  17. Discover the surprising benefits of midday breaks
  18. Revolutionize your workspace with these tips
  19. Out with the old: A fresh approach for success
  20. Supercharge your [task your prospect cares about]
  21. Tripling ROI in just 30 days: Let’s dive in
  22. I promise there are no cat videos in this email
  23. Get personal with [Product’s] latest breakthrough
  24. Saying goodbye to [pain point] once and for all
  25. Uncover the secret to [desired outcome]
  26. Don’t miss out on [exclusive opportunity]
  27. It’s time to [benefit] – let’s get started!

Timely Email Subject Lines

Timely subject lines create a sense of urgency and encourage timely response rates. To make your email stand out in an inbox, tie it to a current event, month, or holiday. Whether it’s Christmas or the start of tax season, leveraging current events can make your email more relevant and personal. An easy way to do this is by adding the year, month, or season. 

It’s always important to be mindful of what is happening in the world and what might be happening in your prospect’s personal life. For example, if you know your prospect’s business wasn’t recession-proof, consider reaching out to someone who may not have so much on their plate.

Example timely cold email subject line.

Here are some timely subject lines that have worked in the past:

  1. How the recession is affecting your industry
  2. 12 inspirational books on cancer to read in 2020
  3. How to reduce waste this holiday season
  4. Friendsgiving decor + hosting idea
  5. Kid’s end-of-summer bucket list ideas
  6. 5 kindness calendars for the New Year
  7. 4th of July historical dessert party printables

And here are some additional ideas you can incorporate:

  1. Act fast – limited spots available for [opportunity]
  2. Don’t procrastinate – [action] before it’s gone
  3. Act now – time-sensitive opportunity inside
  4. Hurry, limited supply available now
  5. Wednesday Wisdom: Don’t miss this insight
  6. Stay informed: latest updates on [current event]
  7. Warm wishes for a joyful [Holiday] season
  8. Discover [Year] holiday trends and traditions
  9. Your [current event] guide for [Year]
  10. Stay safe and informed: [Event] updates
  11. Holiday greetings from our team at [Your Company]
  12. Ring in the new year with [Product/Service Name]
  13. Get ready for [Upcoming Event] – reserve your spot!
  14. Holiday cheers: [Year] in review
  15. New opportunities await amid [current event]
  16. Addressing [current event] concerns: our solutions
  17. Embracing change: [current event] and your [benefit]
  18. Stay ahead in [current event] times with [your solution]
  19. Making sense of [current event] – let us guide you
  20. Friday updates: End of week recap

Follow-Up Email Subject Lines

If the recipient doesn’t reply to your email after a few days, try following up. The best follow-up email subject lines are eye-catching, purpose-driven, and personal. Adding humor to your follow-up email subject line can also be successful.

Example follow-up cold email subject line.

Here are some follow-up subject lines that get emails opened:

  1. I didn’t get to say this the last time we spoke
  2. Here’s how we can get started
  3. Just one more thing…
  4. [First Name]’s invite is waiting…
  5. [First Name], here’s how I can help you this week
  6. I’d love your feedback on [topic]
  7. [First Name], it was a pleasure chatting with you
  8. Any update on [Topic]?
  9. Do you need anything else from me?
  10. Really enjoyed our conversation, [First Name]
  11. A quick follow-up from our last conversation
  12. Ready to begin? Here’s the next step
  13. Just a friendly reminder…
  14. Reflecting on our conversation, [First Name]
  15. Any progress on [topic]? Let’s discuss
  16. Is there anything else I can assist you with?
  17. A gentle nudge on our ongoing discussion
  18. Revisiting [topic] – your thoughts?
  19. Let’s pick up where we left off, [First Name]
  20. Have you had time to review [topic]?
  21. Ready to move forward, [First Name]?
  22. Updating you on [Topic], [First Name]
  23. Checking in: How can I support you further?
  24. [First Name], ready to make progress on [topic]?
  25. Revisiting our plans – [topic] discussion
  26. Ready to dive deeper into [topic]?
  27. Need any assistance, [First Name]? Let’s talk!

Professional Email Subject Lines

Professional subject lines are simple, maintain a formal tone, and get straight to the point. You will often use them when emailing executives or those in serious industries. When writing a professional email subject line, focus on delivering the core message of the email and avoid adding fluff.  

Example professional cold email subject line.

Check out these professional email subject line examples:

  1. Elevating your business strategy
  2. Recap of our recent discussion
  3. [Your Company] Industry News and Analysis
  4. Invitation to an exclusive industry event
  5. How can we enhance your success, [Name]?
  6. Seeking your expertise on [specific topic]
  7. Presenting our latest solution
  8. Let’s synchronize our growth strategies
  9. Optimal approaches for achieving [specific goal]
  10. Time-sensitive: Respond by [date] required
  11. Gain insights from our upcoming webinar
  12. Exclusive offer tailored to your needs
  13. Enhance your X strategy with our new E-book
  14. Connect with other experts in the finance industry
  15. Ready to overcome your obstacles?
  16. Personalized solutions for your business
  17. Revamp your approach to [X] with expert guidance
  18. Collaborate with industry authorities
  19. Strategizing for your business’s future
  20. Stay informed with [Your Company] insights
  21. Invitation to our top-tier industry webinar
  22. Your expertise requested, [Name]
  23. Maximizing success with your input
  24. [Your Company] newsletter and updates
  25. Streamlining your approach to [X]
  26. Aligning strategies for mutual growth
  27. Important update about our collaboration

The Best Cold Email Subject Lines We’ve Used

Out of the 100 email campaigns we studied, below are the top five best cold email subject lines with the highest open rates.

Our best cold email subject line.

As you can see from the data above, cold email subject lines that are timely, specific, and relevant to your specific prospect are the most successful.

Take the time to craft a thoughtful subject line like a blog post title — creative subject lines are crucial to increasing your CTR.

Conclusion

Whether you’re writing a sales pitch or promoting your new blog, the tips above can help you create perfectly crafted cold email subject lines that work. Remember that good cold email subject lines are relevant and resonate with the recipient. 

In addition to the subject line, other factors you should consider are the time of day you send the email, the call-to-action, and the email format. Feel free to play around with these factors and see for yourself what works best. Or, use an email template to help you get started.

At Siege Media, we use these subject line tips to generate external links for our clients. Check out our digital PR services to learn more. 

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