Writing Subject Lines That Drive Engagement

by The Giles Agency

At The Giles Agency, we do a lot of work on eDMs, from regular newsletters and brand messaging to promotional campaigns and important notifications. What they all have in common is the need for a strong subject line that will drive engagement. So how can you craft a subject line that’s guaranteed to get results?

Let’s start with the key elements of a strong subject line. We believe subject lines should be two things – clear and enticing.

Firstly, clear. A subject line should tell the reader what the email is about. It’s important to avoid being misleading here. The expectations set by the subject line must be met in the email or you risk damaging the trust you’re building with your reader. However, that doesn’t mean you need to give it all away. Alluding to the topic, without giving all the details is great way to arouse curiosity.

Here are a couple of examples:

  • A simple tool to transform your accounting
  • The HR fair you cannot miss

A subject line should also be enticing, giving the reader a compelling reason to open it, and open it now. This can be achieved in a variety of ways.

You could highlight a benefit, like in this example:

  • Recycling tips that will save you money

Or you could create a sense of exclusivity, urgency or scarcity, like in these examples:

  • Your invitation to our VIP pre-sale
  • Earn double loyalty points today only
  • NLP Seminar – only three spots left

Copywriting and editing subject lines is a key skill

Once you have the basics right, there are a few little tricks and add-ons to add further oomph. We like some of them more than others, and here are a couple to consider with a degree of caution, only if they’re on-brand for you.

Controversial / Shocking

A shocking subject line will indeed garner more attention, once. However, if the subject line isn’t directly connected to what’s in the email, readers will feel misled. They may open the first email they receive from you, but those numbers will likely drop off in subsequent emails.


Emoticons are becoming more and more common and we’ve seen some really fun and creative uses. They’re friendly, personal and emotional – all the things good copy should be. However, proceed with caution. Emoticons are of course very informal and don’t work for all brands.

Here are some less risky ways to amp up your subject line:


Using the reader’s name, as in “We have a gift for you, Amy” or location, as in “Cirque de Soleil is coming to Taipei” is a simple and effective way to grab your reader’s attention and make them feel like you’re talking directly to them (which should always be your aim). Just remember this approach is better suited to promotional emails than company news.


An easy way to create curiosity is to suggest you have something new and exciting to say. This can be done very simply by starting your subject lines with ‘Announcing…’ or ‘Introducing…’.


Questions are a great way to focus the reader’s attention. When we’re asked a question, our brain reacts involuntarily to answer it, forcing us to engage. A question without an answer is unsatisfying and we’re likely to go looking for that answer even if we’re not particularly interested in the question!

Now let’s take a look at how long your subject line should be. The golden rule here is keep it short. The majority of your readers (usually between 60 and 80%) will read your eDM on their phone, so think mobile first. How much of your subject line will they be able to see on their screen without opening the email? It varies, but let’s take an average of 30 characters. So aim for 30 characters or fewer, or between four and seven words. After that, it will be truncated.

Now, like all good rules, it sometimes pays to break this one. On occasion, it’s better to use a couple more words than to leave important things unsaid. It also depends on how those words are arranged as it’s often possible for the reader to guess the final words of a subject line when the gist of the message is captured in the first few.

Subject lines are incredibly important so it pays to put time and effort into getting them right. Come back soon to check out our coming article on how to judge the success of your subject line and adapt accordingly.