Email Subject Lines

How to Increase Your Email Open Rates


Depending on the industry, your email open rates should average between 15-20%. So what if you’re not seeing those types of numbers? The solution could be as simple as a subject line adjustment.

If you’re not getting the open rates you desire, your subject line could be the culprit. It's the first the reader sees of the campaign after all. It all lies in an intriguing subject line to encourage the reader to make that first click to read the email. It needs to be captivating and engaging or it will get ignored.

Writing clickable subject lines can be a daunting task, but subject line formulas can help. There are a number of formulas which researchers have discovered that can be the key to encouraging readers of open your emails and therefore increase your open rates. We've picked out our favourite 3 below. These are the ones we feel most commonly work best across all industries and are the ones we reccomend to our clients. Simply tweak each formula to fully fit with your topic and industry.


The “Scarcity” formula


The scarcity subject line formula works because urgent emails get clicks. A fear of missing out encourages people to act fast, clicking the email to find out more and ensure they aren't missing anything. Adding a date or availability encourages people to open the email before it's too late.

Some examples might be:

  • "Only 2 days left to get 50% off!"
  • "Free delivery for today only!"
  • "Hurry! Final 10% of tickets left!"

This kind of email highlights limited-time offers. The scarcity factor entices subscribers to find out more from fear of missing out if they don't. The key to using this formula is to ensure the information on offer is of interest to the people on the email list. Scarcity only works if the person is already interested in what is on offer. If it is irrelevant to them they won't bother clicking. You must ensure that the offer you are presenting is important to the reader before you use scarcity to compel them to act quickly. Otherwise it will have no effect.


The "How-to" subject line formula


How-To subject lines promise to give the email receiver information they want whilst describing the content of the email clearly. When you know exactly what the email is about you know in seconds whether it is of interest to you. So by combining a popular intriguing topic with the 'How-to' formula your email becomes irresistible to open!

Some examples of the how-to subject line formula:

  • "How to get 500 new Instagram followers today."
  • "How to Improve Social Media Interaction"
  • Or even the title of this blog: "How to Increase Your Email Open Rates."

They key to a successful 'How-to' subject line is to focus on the benefits. Tell people what they want and then how to achieve it. Entice them in to read more.


The “Curiosity Gap” formula


The curiosity gap is why we see movies or read clickbait. When you hook your audience a little, they usually want the whole story. The formula originates from the psychological phenomenon known as the curisoty gap, which is a term used to describe the gap betweens what we know and what we want to know. When we realise we don't quite know it all, a feeling of deprivation prompts us to go and find out more. Once we know a little piece of information our curiosity peaks and we just want to know more.

Here is some examples:

  • "I ate only vegetables for a month and this is what happened."
  • "This little known trick can help increase your website traffic."
  • "9 out of 10 designers make this mistake."

The subject lines using this formular reveal just enough information to pique the reders curisoity, compelling them to click the email to read more.


Whatever formula you use, make sure your content delivers value. If you promise something and don’t deliver, you could lose subscriber trust and engagement. Your subject line is what entices your reader to open your email and read the information inside, so it’s important to put some thought into this part even if it seems small and insignificant. In some ways the subject line is more important that the content! There are many ways to write an interesting, compelling subject line based around the few tips we’ve provided here. You can also test different types of subject lines to see which ones work best for your unique audience, as it all comes down to what your audience is looking for and is therefore indiviudal to your brand.

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