Subject Lines 101 – tips for getting people through the door

As the old adage goes: ‘You should never judge a book by its cover’. Fortunately for the designers at your favourite publisher, the vast majority of us stubbornly refuse to follow that advice.

We like to know that what we’re about to invest our time in is going to be worth it. And the best way to do that is to, well, see if the cover looks promising.  

Your subscribers’ inboxes are all their own personal little book stores. And your subject line – i.e, your cover – is the first thing standing between a browser and a customer. Getting them right is one of the most crucial parts of any email campaign. Opens are the first step – and if your subject line doesn’t make the cut, your email might be left behind.

Like designing a book cover, writing a good subject line is an art. But it’s also a science. There are a few tips and tricks you can follow to help make sure your open rates stay strong. Let’s take a look.


First up – personalisation. Use your subscribers’ names occasionally, but don’t overdo it. Try and keep it natural, especially if your campaigns are quite regular.  

Personalisation doesn’t have to just end at a name, though – even in a subject line. For example, segmenting your subscribers based on their location could allow you to reference their home state or country, making your campaign even more relevant.

Find out more about segmentation here.

Getting personal with your subscribers helps you to retain them for life. In ecommerce, relevance is king.

A few examples:

  • “Trying to cool off in the summer heat, [Firstname]?”
  • “20% off [Subscriber’s Country] Flags!”

Short and sharp  

Subject lines don’t give you a lot of room to work with.

It’s reported by Return Path that the optimal length is around 61-70 characters. However, as more and more email is read on mobile devices, we might even need to aim to make our subject lines even shorter. Hook your readers in quickly with a short, sharp subject line.  

A sense of urgency

Adding a time limit or call to action in your subject line is a great way to get people to open.

By creating a sense of urgency, you’ll encourage more people to open your emails out of fear of missing out.

  • “Don’t let these hot Winter specials freeze over!”  
  • “50% off for a limited time!”

Keep it on brand

Your subject line should be designed to convert. But that doesn’t mean you need to throw your voice and tone out the window.

People will only subscribe to your mailing list if they like your brand. So ensure you’re keeping all your content – from your website copy, to video scripts, to product descriptions (and yes, subject lines) – consistent.

If you use a lot of emojis on social media, chuck a few of them in there! But if you keep your brand more serious and authoritative, don’t use emojis – even if some say they increase open rates. Your brand needs to be kept intact.


It’s a common misnomer that deliberately incentivising language gets picked up by spam filters. It’s also a common misnomer that deliberately incentivising language is ‘clickbait’. Clickbait is only clickbait when it doesn’t deliver what it promised.

If you’re offering a discount – state it clearly and deliberately in the subject line. If you’re giving away a free gift with every purchase of a premium package deal, you can and should use ‘Free gift’ from the word go!

These days, spam filters are far more concerned with the reputation of your sending domain than they are with the contents of your subject line.

  • “Buy now and we’ll ship your order free!”
  • “EOFY! 30% off storewide”   

A/B Testing

Powerful new email marketing platforms easily allow you to test different variants of your subject lines to see which ones receive the most opens. This is a great way experiment and optimise your subject line style.

See what works best with your audience. Test what kinds of personalisation work for you. Do your audience respond well to being called by name? Do they prefer shorter or longer subject lines? Do they like emojis? Do they just want the specials?

‘A/B tests’ are a powerful tool to put to work for your email marketing strategy. If you need help setting up your own optimised email campaigns, let us know! We’d love to help out.    

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