Lady using her mobile phone with a grassy background

The art of the email subject line

The art of the email subject line

Posted on 05 April 2017 by Jason

Campaign Monitor recently sent me a link that caught my eye. It was titled "8 subject line formulas that will get your emails opened". It clearly worked - I opened the email.

In the article, they go on to list the most popular ways that people are using to engage consumers in their e-marketing activity. I found it interesting, so thought I'd summarise what they found here. The link to their page can be accessed at the end of this blog.

1. Use a question in the subject line

Questions will resonate with the recipient and their past experiences. They will also arouse a sense of curiosity to learn more about the subject and whether or not their experiences are similar to others.

  • Do you want to achieve world domination?
  • Would you accept a knighthood?

They are effective as the reader can likely relate to these behaviors (at least in the Campaign Monitor examples anyway). It also encourages them to open your email and learn more about what the possible implications of that behaviour is.

2. Using 'How To' in the subject

Apparently, there’s an old saying in copywriting circles that you can’t write a bad headline if it starts with the words ‘How to’. News to me. Still, I bet there are people that make a right pig's expletive of it.

Anyway, the ‘How to’ subject line formula works well as it forces you to describe the content of the email in very clear language. For example:

  • How to achieve world domination from your couch
  • How to get yourself a knighthood

The key to success is focusing on the benefits of the email. They want the benefit that this process or methodology will give them, such as better marketing results or 1000 new email subscribers. It's key to focus on the end benefits the recipient will get rather than the process itself when using the 'How to' subject line.

3. The short and sweet subject line

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 recipients to open and act before it’s too late. For example:

  • Only 25% of the world is left for domination!
  • HURRY! Only 4 knighthood spaces remain

It's important that the offer you present is important to the reader before you bring scarcity in to compel them to act quicker. If not, the time or availability limitation you are imposing isn’t really relevant to them.

4. Use an announcement as the subject line

A recent study that Campaign Monitor carried out showed that using power words like ‘Introducing’ and ‘New’ in the subject line increased the chance of the email being opened by 9.45% and 3.26% respectively. Examples may include:

  • A new tactic for dominating the world!
  • Update to your knighthood invitation... 

By using these power words, 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.

5. Using numbers in the subject line

Apparently, by using numbers in the subject line you can set people’s expectations and provide a structure for the content of your email.

Campaign Monitor say that every time they A/B test their blog headlines, they find that the version of the headline containing the number outperforms the one that doesn’t. Examples may include:

  • 7 more towns until you've dominated the world
  • 6 reasons we're rescinding your knighthood

The key is to carefully choose the number you use. If you are suggesting effort that a user will need to use (e.g. ‘5 steps to drop that holiday weight’), then using a low number works well, as it suggests the process is quicker and easier.

However, when providing value to the reader e.g. ‘10 tricks to increase email subscribers’) then a higher number will be more effective as it increases the reader’s perception of the value your email will provide.

6. Use curiosity (we call it clickbait) as a tool

Clickbait produces a feeling of discomfort that compels users to go looking for a piece of missing information.

Maybe it's worth leaving a small curiosity gap in your subject lines to encourage subscribers to open your campaigns. For example:

  • This guy achieved world domination by making this one change to his BBQ setup
  • You'll never believe why this man's knighthood was taken back

Clickbait subject lines leave just enough information trigger curiosity. By using these types of subject lines, you tease people to open the email and learn more.

7. Use a surprise in the subject line

Everyone loves pleasant surprise. Studies on brain activity show simple unexpected occurrences light up the pleasure centers of the brain and result in  happiness.

Using surprise in your subject line triggers an emotional response that increases the chance they’ll open your email. For instance:

  • Why Pingu was a fascist
  • We've given your knighthood to your traitor best friend

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

Apparently, Barack Obama's team used the subject line ‘Join me for dinner?’ in one of their email campaigns. Whilst it is certainly not a surprising subject line, the fact that it came from the POTUS certainly surprised a few people.

8. Personalise the subject line

By using your subscriber’s name in the subject line of your email, you can  add a personal touch that is likely to catch their eye. 

A recent study showed that using the recipient’s first name in the subject line increased the chance of the email being opened by 14.68%.

Use it with other formulas for greater effect:

  • Jason, forget about dominating this world - conquer the solar system!
  • Tommy - How you can frame your 2 friends for the knighthood fiasco

Including the reader's first name, you create a feeling that you are speaking directly to them. This gives your email a sense of relevancy that encourages them to open it and read the content.


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

You can check out the original Campaign Monitor article (which is far more coherently written than this one) using the link below.

Source: Campaign Monitor

Tagged In

Like what you're reading?

If you'd like professional support to kick-off your digital marketing strategy or if you have a project brief you're ready to share we'd love to hear from you...

Get in touch