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

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

You may feel like the body of your email is your bread and butter—the most important part. And while what you write in your email is crucial, it’s the email subject line that really counts.

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

Sending carefully crafted subject lines are how we promote the content we create and as a result, build links for our clients. Just look at how we were able to build 700+ links in the finance space—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 truly makes a successful cold email subject line.

Cold email subject line examples:

How to Make a Great Cold Email Subject Line

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.

When analyzing 100 email campaigns in a variety of industries, we found that email subject lines roughly 64 characters—with an average word count of 10—were the most successful.

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


The “reason you’re reaching out” section is in reference to what you’re promoting or asking for. For example, if you’re reaching out to schedule a meeting your email subject line would look a lot like this:

Meeting for Kiera: Influencer marketing strategy

If you’re reaching out to share a guide your company just created you would write:

Guide for Jarrod: 7 ways to grow your business today

Pretty straightforward, right?

The next section is a bit trickier. You’ll want to summarize the reason you’re reaching out in a thought-provoking, yet concise manner. Are you launching a new copywriting service? Promoting your new product? Summarize why you’re reaching out 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

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 a lot of business owners face. Prospects are more likely to open an email with a good subject line that doesn’t feel too salesy, but instead is conversational and helpful to them.

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. Read on for 45 successful subject line examples from the Siege team themselves.

Personalized Subject Lines

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

Just like your email template, your subject line should be personalized. The easiest way to do this is to use the prospect’s name. When sifting through a full email box, people are more likely to stop on subject lines that include their name. If you can’t find their name, use their company or product name. If you have a mutual connection with your prospect, make sure to 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? Launch a new website? Write an interesting article? Mention that in your subject line. It will make them feel important and they’ll be appreciative you did your research beforehand.

personalized subject line example

Here are some examples of personalized email subject lines:

  • Congratulations on [Event]!
  • [First Name], do you have 5 mins?
  • [First Name], here’s how you can crush Q3 goals
  • [First Name], have you been taking care of your mental health?
  • [First Name], I had a question about your recent article

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 moved to remote work, consider asking them a question on how it’s going. Not only is this question timely, but it hits a pain point for a lot of business owners right now: managing a remote team. Once they open your email, let them know how your product or service can help.

Here are some great question subject line examples in action:

  • Are you financially responsible for a pet?
  • Is it time to open a new business location?
  • Can you afford to move out?
  • How safe is your neighborhood?
  • Have you heard about [Subject]?
  • Thoughts on [Subject]?
  • 10 minutes next week?
  • Should you monitor your remote employees?
  • Have you been feeling [Emotion]?
  • Can you meet on [Day]?
  • Is your ego sabotaging your small business?
  • Should your business accept cryptocurrency?
  • What do your dreams mean?
  • Is it time to scale your business?
  • How much should entrepreneurs pay themselves?

Attention-Grabbing Subject Lines

It doesn’t matter how great your email or sales pitch is if no one opens it. A great way to get your email opened and read is to create a subject like that grabs your prospect’s attention. Typically an attention-grabbing subject line will include something shocking, controversial or compelling

You can do this 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

attention grabbing subject lines

Here are some examples of attention-grabbing subject lines:

  • Science-backed benefits of napping at work
  • Self-care isn’t just for Sunday
  • Study: Your steering wheel is 4X dirtier than a public toilet seat
  • +[XX]% in revenue for businesses that add this to their site
  • EXCLUSIVE: You’ve been invited to…
  • Did you hear what happened?
  • Only X weeks left to achieve [Goal]

Timely Email Subject Lines

Timely subject lines create a sense of urgency and encourage timely response rates.

You can make your subject line timely by adding in the year, month, season or by referencing a specific event that is going on in the world.

time sensitive subject lines

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

  • 72 Coronavirus statistics
  • 12 inspirational books on cancer to read in 2020
  • How seniors can protect themselves from Coronavirus
  • How to reduce waste this holiday season
  • Friendsgiving decor + hosting idea
  • Kid’s end-of-summer bucket list ideas
  • 5 kindness calendars for the New Year
  • 4th of July historical dessert party printables

Follow Up Email Subject Lines

If your email isn’t getting a response after a few days, try following up. The best follow up email subject lines include something eye-catching, purpose-driven and personal. Adding a little humor to your follow up email subject line can also be successful.

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

  • I didn’t get to say this the last time we spoke
  • Here’s how we can get started
  • Just one more thing…
  • [First Name]’s invite is waiting…
  • [First Name], here’s how I can help you this week
  • I’d love your feedback on [TOPIC]
  • [First Name], it was a pleasure chatting with you
  • Any update on [Topic]?
  • Do you need anything else from me?
  • Really enjoyed our conversation, [First Name]

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.

best email subject lines

Cold email subject lines that are timely, specific and relevant to your specific prospect are what are the most successful. Take the time to craft a thoughtful subject line just like you would a blog post title. Just like blog titles, creative subject lines are crucial to increasing your CTR.

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:

Make it Timely

To make your email stand out in an inbox, tie it to a current event, month or holiday. Whether that be Christmas or the start of tax season, leveraging current events can make your email feel more relevant and personal.

It’s always important to be mindful of what is going on in the world and what might be going on in your prospect’s personal life. For example, if you know your prospect’s business was hit hard by the COVID-19 pandemic, consider reaching out to someone else who may not have so much on their plate.

Make it Personal

Personalized email subject lines have been proven to boost open rates. Including someone’s name is a great place to start, however, the more personalization you can add the better. Consider what may be going on in their life. Did they just start a new job? Launch a new product? Reference that in your sales subject line and use casual language to encourage more open rates.

Make it 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 by 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.

Whether you’re writing a sales pitch or promoting your new blog, the tips above can help you create a perfectly crafted subject line that is sure to get opened.

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