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9 Subject Line Formulas That Are Sure To Get Your Emails Opened

If you find it difficult to come up with great subject lines for your email campaigns, don’t worry – you’re not alone!

205 billion email messages per day, which means almost 2.4 million emails are sent every second and some 74 trillion emails are sent per year. That means the average person gets 88 emails per day and of those only about 30% get opened. Eeek!

The subject line is the start of the reader’s experience and often your only chance to get their attention, especially in a world of increasing distractions, So it needs to be captivating and engaging, or all that hard work of yours will be out the window.

So to help you write a great subject line that engages your readers and gets your emails opened, here are 9 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 stop and think about how what you’re asking them applies to their own life.

The best questions will resonate with the reader and their past experiences, peaking their curiosity to learn more.

For example:

Do you check your emails even after you get home from work?
Do you need coffee to become functional in the morning?

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

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’.

This particular formula works so well because it forces the writer to present the article in a very clear and easy to understand way, which makes it easier for the reader in turn to absorb the information. Take these 2 subject lines for example:

How to get more out of your morning routine
How to get increase your ROI with Social Media
How to decorate your home like a pro

By reading these subject lines, your subscribers know exactly what they are going to get from the get go and are compelled to open your email to find out more.

Word of caution with this formula though, the key to success with this subject line is focusing on the benefit, rather than the method. If it sounds like too much effort upfront then it’s easier to bin it or ignore it.

3. The scarcity subject line

Scarcity is a powerful driver of human behaviour. When something is in short supply, FOMO (our fear of missing out) kicks into overdrive and we can’t help but take action.

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

Only 24 hours left to get 50% off fitness watches
Hurry! Only 3 spots left for our Summer Seminars

The key to using scarcity is relevance. If the reader has no interest in fitness watches, they are not going to care that there’s only 24 hours left to get 50% off them. You need to make sure your offer is for something that is important or appealing to them.

4. The announcement subject line

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

Examples of this formula in action include:

Introducing our new Winter line
Update to our iPhone App

Check out our new bathroom designs

By using words like ‘Introducing’ and ‘New’ in the subject line, you are letting your readers know that what you’re about to present to them they didn’t already know, so don’t let it be a false hope. Only use this headline if what you’re offering is actually new. If they saw it in your emails or on your website last week then it will be a letdown and damage your credibility.

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 or article link.

When Campaign Monitor 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:

20 easy ways to build your email list
5 steps to sending getting your brand message right

The key to success with this formula is carefully choosing the number you use. If you are suggesting effort a reader needs to expend (like ‘5 steps to lose that baby weight’), then using a lower number works better as it makes the process is quicker and easier. However, if you’re providing value, then higher numbers work better (like “10 tricks to grow your Instagram followers) as it gives better-perceived value.

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 already know and what we want to know’. When we notice there is a gap in our knowledge, it gives us an uneasy feeling and a need to fill that gap.

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

This guy asks the most basic question ever, and stumps our smartest politicians
This little-known hack will increase your click-through rates
4 out of 5 Aussies are completely wrong about this one simple thing

As you can see, these subject lines leave just enough information out to pique the reader’s curiosity. What is the simple thing that 5 out of 5 Aussies are wrong about? Am I wrong about it too? This compels 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. And seriously we could all do with a little more happiness!

Whether it’s a clever pun or an unexpected offer that benefits the user, using surprises in your subject line triggers an emotional response which increases the chance readers will open your email. For example:

What Taylor Swift can teach you about marketing
Don’t let the fairies make off with your empty shopping cart!

The key here is 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 personalised subject line

People are programmed to recognise their name. Have you ever yelled some’s name in a park and 3 other people turn around looking a little confused? Working your subscriber’s name into the subject line of your email not only adds that personal touch, but makes the reader feel like you’re sincere and reaching them on a personal level – they’re not just another name on the database.

When combined with some of the other formulas you can even double your impact. For example:

Tiffany, do you need coffee to become functional in the morning as well?
Jason, don’t miss out on this little-known hack will increase your click-through rates!

Isabella, there is only 24 hours left to get 50% off fitness watches!

Word of warning with this one though – make sure your database has no gaps so you don’t end up with a subject line like this “<FIRST NAME> do you need coffee to become functional in the morning as well?” That will probably tick people off more than make them want to read your email!

9. The emoji subject line

This is relatively new, and probably only relevant to certain brands depending on the demographics of your email database, but can be really effective in making your emails stand out. Just that extra bit of colour on a largely white screen will automatically catch the eye of readers, and coupled with another formula how could you go wrong? For example:

Everyone is a winner with this simple to use product
50% off puppy food for 1 week only

This won’t be suitable for everyone, like for example if you’re a financial adviser to high-wealth clients it might come across as tacky. So use this one with consideration, but if it fits your brand or your product then give it a go.

In Conclusion

Your subject line is like the dinner bell calling people to come check out what’s on offer, but if you get it wrong or don’t ring loud enough, chances are they will go somewhere else. That said, we know it can be hard to consistently create great subject lines, so give some of these ideas a go, and as always if you need any extra help we are here with any questions you might have.

Christie McDougall

Christie is our Social Media Strategist. With years of Social Media experience, she has an incredible ability to write great copy and strategy for each campaign. She has worked for many different organisations in this space and has a great understanding of how to create ads and build campaigns that potential customers respond to.

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