Do you find it difficult to come up with great subject lines for your email campaigns?

The subject line is the start of the reader’s experience with your campaign, and in a world of increasing distractions, it can also be the end of their experience if you don’t make it captivating and engaging.

So to help you write a great subject line that engages your readers and gets your emails opened, here are 8 subject line formulas that you can use in your upcoming email marketing campaigns.


1. The question subject line

Questions make great email subject lines because they get the reader to think about how the subject matter applies to their own life.

The best questions will resonate with the reader and their past experiences, while arousing a sense of curiosity to learn more about the subject and whether or not their experiences are similar to others.

For example:

  • Do you check your emails when you first wake up in the morning?
  • Are you a zombie without your morning coffee as well?

These subject lines work because the reader can likely relate to these behaviors, and it compels them to open your email and learn more about what the possible implications of that behavior are.


2. The ‘How to’ subject line

There’s an old saying in copywriting circles that you can’t write a bad headline if it starts with the words ‘How to’.

The ‘How to’ subject line formula works so well because it forces you to describe the content of the email in very clear language. Take these 2 subject lines for example:

  • How to get better marketing results through beautiful design
  • How to get 1,000 new email subscribers in 1 day

By reading these subject lines, your subscribers know exactly what they are going to get from opening the email and are compelled to do so.

The key to success with this subject line is focusing on the benefit. Nobody actually wants to learn another process or methodology, instead what they want is the benefit this process or methodology will give them, such as better marketing results or 1000 new email subscribers. So make sure when using a ‘How to’ subject line you focus on the end benefits the recipient will get rather than the process itself.


3. The scarcity subject line

Scarcity is a powerful driver of human behavior. When something is in short supply, our fear of missing out kicks in and we are compelled to act.

Adding a time or availability limitation encourages readers to open and act on your email before it’s too late. For example:

  • Only 2 days left to get 50% off shoes
  • Hurry! Only 3 consultation spots left.

The key to using scarcity in your email subject lines is relevance. If the reader has no interest in buying shoes from you, they are not going to care that there’s only 2 days left to get 50% off them. You need to make sure the offer you are presenting is important to the reader before you bring scarcity in to compel them to act quicker, otherwise the time or availability limitation you are imposing isn’t really relevant to them.


4. The announcement subject line

Using words like “Introducing” and “New” in your subject line gives the reader a feeling that your email contains new, breaking information they haven’t heard yet.

In our recent study on power words in subject lines, we found including words like ‘Introducing’ and ‘New’ increased the chance of the email being opened by 9.45% and 3.26% respectively.

Examples of this formula in action include:

  • Introducing a better way to send emails
  • Update to our iPhone App
  • See our new design gallery

By using words like ‘Introducing’ and ‘New’ in the subject line, you are letting people know that your email contains new information they don’t know yet and are encouraging them to open the email and learn more.


Explore more subject line hacks


5. The number subject line

Using numbers in your email subject lines is a great way to set people’s expectations and provide a structure for the content of your email.

Every time we A/B test our blog post headlines, we find that the version of the headline containing the number outperforms the one that doesn’t.

For example, when we A/B tested the subject line ‘3 steps to measuring the success of your email marketing with Google Analytics’ against ‘How to measure the success of your email marketing with Google Analytics’, the subject line with a number got a 57% increase in opens.

So when possible, use numbers to make your subject line more specific. For example:

  • 30 ways to build your email list
  • 3 steps to sending beautiful email campaigns with Campaign Monitor
  • 10 product announcement emails reviewed for conversion

The key to success with this formula is carefully choosing the number you use. If you suggest effort a reader needs to expend (like “5 steps to drop that holiday weight”), then using a low number works better as it suggests the process is quicker and easier.

However, if you are providing value to the reader (like ‘10 tricks to increase email subscribers’) then a higher number will work better as it increases the reader’s perception of the value your email will provide.


6. The curiosity gap subject line

Viral content sites like Buzzfeed have built publishing empires on the back of a psychological phenomenon known as the curiosity gap.

Professor George Loewenstein coined this term to describe the gap between what we know and what we want to know. When we notice a gap in our knowledge, it produces a feeling of discomfort that compels us to go looking for that piece of missing information.

So try leaving a small curiosity gap in your subject lines to encourage subscribers to open your campaigns. For example:

  • Dave Richardson asks the most basic question ever, and stumps our smartest politicians
  • This little-known copywriting trick will increase your email click-through rate
  • 9 out of 10 Australians are completely wrong about this simple fact

As you can see, these subject lines leave just enough information out to pique your curiosity. What is the question Dave asked that stumped the politicians? Would I be able to answer it? And what is the simple fact that 9 out of 10 Australians are wrong about? Am I wrong about it too? By using these types of subject lines, you provoke the sense of discomfort created when a curiosity gap exists, and compel people to open the email and learn more.


7. The surprise subject line

Everybody loves a good play on words or a pleasant surprise. In fact, studies on brain activity show that these simple unexpected occurrences light up the pleasure centers of the brain and cause happiness.

Whether it’s a clever pun or an unexpected offer that benefits the user, using surprise in your subject line triggers an emotional response in the recipient that increases the chance they’ll open your email campaign.

Some examples include:

  • Warning: Unattended items in your shopping cart may be eaten by gnomes
  • What Elvis Presley can teach you about email marketing

The key here is not so much to structure your subject lines in a particular way or use any specific words, but just to surprise the reader with something they wouldn’t expect.

In fact, during Barack Obama’s presidential election campaign his team used the subject line ‘Join me for dinner?’ in one of their email campaigns. While ‘Join me for dinner?’ is certainly not a surprising subject line, the fact that it came from the President of the United States certainly surprised a few people.


8. The personalized subject line

Working your subscriber’s name into the subject line of your email adds a personal touch that is likely to catch your reader’s eye. Anytime you can make your reader feel like you’re connecting with them on a very personal level, it builds a sense of sincerity.

In fact, in our recent study on power words in subject lines we found that using the recipient’s first name in the subject line increased the chance of the email being opened by 14.68%.

This can be combined with some of the other formulas for maximum impact. For example:

  • John, are you a zombie without your morning coffee as well?
  • Amy, 9 out of 10 Americans are completely wrong about this fact.
  • Paul, there’s only 2 days left to get 50% off boots.

By including the subscriber’s first name, you create a feeling that you are speaking directly to them and give your email a sense of relevancy that encourages them to open it and consume the content.


Want to learn more about creating subject lines that ramp up your opens? Keep reading.


Wrap up

Your subject line is what entices your reader to open your email and pursue the information inside, so it’s important to put some serious thought into this portion of the campaign creation process.

That said, we know it can be hard to consistently create great subject lines, so take some of these ideas and put them to work in your campaigns today.

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