Evolve your email marketing with A/B Split testing

It’s been a busy day, you and your team have been working hard on this week’s email newsletter. It’s looking good, the content is fresh and relevant, you’ve got something to say to your readers. In fact you’ve been focusing so hard on the content that you haven’t really had the time to take a step back and reflect on your overall email strategy. The weekly newsletters are doing well, lots of opens and a good click through rate. The conversions are always good, so you are confident that what you’re doing is right – it’s working well, after all.

But, could it be better? A small increase in conversions could mean a big uplift in revenue generated. A few more social shares and the reach of your brand is significantly increased.

In the always busy world of email marketing it can be difficult to make time to try out new approaches, talk to your audience in a different way. Aside from the resource hurdle there’s the risk factor too. Dare you put all your eggs in one basket with your weekly newsletter? What if the new tactic doesn’t improve results, or worse, performs less well than the tried and tested usual way?

It doesn’t have to be this way. Whilst the digital world enables us to be agile and disruptive, pushing boundaries, a safe way to evolve your email marketing strategy exists and it’s more than likely already at your fingertips – multi-variant split testing (or simple A/B Split testing).

To always be testing should be one of your (many) email mantras. Your programme arrived at its current stage by being tested on some level during its development. If you can speed up the evolution process then your strategy can only grow and improve at a faster rate. Which is, after all, what we are all looking for – better results, improved ROI, simplified processes.

Sounds fair enough, how do you put this A/B Split testing into practice?

There are many elements that make up your email message and each has it’s own effect on the performance. The mail from and subject line will have a key influence on whether your email is actually opened by the recipient. Once opened, timing of the send and the layout of the content will determine engagement with your message. Even the colour and shape of your CTA buttons will affect the performance of the email newsletter.

There’s a lot of elements to be tested, where on earth do I start?

If you aren’t testing any elements at the moment then its a good idea to start small, use A/B split tests on the obvious factors. Since performance ultimately rests on how many people read your message, testing the mail from and subject lines is a great place to start.

Using the A/B Split Test feature in your the email solution that you have (if your ESP doesn’t have this feature then it’s definitely time to take a look around at other providers on the market!) you should decide on a simple subject line test – running three different subject lines against each other.

Typically this involves selecting the number of splits and the ‘winning’ factor (in this case Opens). You then define the testing window, e.g. 3 hours. You then broadcast your newsletter as normal, except in this instance three different versions, each with a differing subject line, will be mailed. But to only a small proportion (e.g. 10%) of your database. Once your time-frame is over the ‘winning’ version will rolled out automatically, to the remainder of your database.

This simple and quick method gives you the opportunity to try different styles of email subject line. You can put the usual against a quirky line against an informative line. What you use depends on the content and aim of the email you are sending.

With this easy to implement test you can send 3 or more different versions of your newsletter every time you broadcast. Confident that the best performing version will always be seen by the vast majority of your audience. Each weekly iteration evolves your email programme.
Very soon you will have moved from the safe, but not necessarily ideal, variant and be confident that you are serving your customers messages that appeal to them.

As mentioned above, the subject line is just one factor to test. Once the benefit of testing has been shown you are now in the position to begin the journey towards testing nirvana. It can be seen that slight variations in design – from layout through themes to button shape and placement, etc.

Use A/B Split testing on these elements to find out which works best for your audience:

  • Subject line style – quirky or dry, % discount or amount saved, etc.
  • Mail from – does a person’s name or the business name speak to your audience better?
  • Time of Day / day of the week – even with the rise of always on mobile devices, timing can be crucial.
  • Image or copy heavy design
  • layout styles
  • button shapes / placement

Do we need another post on email subject lines?

My answer to that question is of course yes.

In the well documented crowded inbox only the strong will survive. It is essential to dedicate part of your email campaign planning process to crafting the best subject line that you can. The email subject line is a powerful thing, in conjunction with the Mail From it should be thought of as the headline for your content. The right headline will draw readers in to your article. In the same way the right subject line will drive recipients to open an email. The From Line reinforces who you are and goes some way towards explaining why your message has landed in your customer’s mailbox. The subject line shows them why they should pause and read on.

Is there a perfect subject line?

If we agree that content creation is an art-form, then it follows that there can’t be a one size fits all answer to this question. This doesn’t mean that you should give up searching and just plump for the safe bet. A few simple pointers can move your email subject lines from the mundane to the truly compelling, urging your readers to open their emails.

A compelling email subject line will reinforce your brand, engage your customers and improve your email deliverability.

Elements to play with

Subject line Length

Research on subject line success will always look at the length. And it will always show that there is no ideal length. The type of message and the audience, or expected response, will play a large role in what works, lengthwise. But the importance of the email clients that your emails are read in should not be overlooked. A number of email clients, and especially mobile devices, may truncate your lovingly crafted subject line. Consider front loading the headline, then if it does get truncated then you still get the thrust of your message across.


The subject line must make your recipients want to read on. But the content must deliver on that promise. Email marketing lives and dies on the relevance of the content. If the subject line promises one thing and the content delivers something else entirely then your customers will feel duped. This is not what you want.

Use teasers

Posing a question in the subject line is a good idea. If the topic is compelling, then there’s little in the way to stop the reader opening your email to find out how they can benefit from your offer.

The Spammers seem to have the right idea

No they don’t. If your subject line in any way, shape or form makes you think of spam then stop and immediately rethink. You’re allowed to go for a walk first, to get some fresh air. Then relax, start over.

Special characters

A not so new tactic is the use of special characters in subject lines. In the early stages of this discovery they were a great way to stand out from the crowd in the inbox. It wasn’t long before everyone was all over this new trick, and special characters soon saturated the inbox. Things have calmed down a bit now and it is certainly worth experimenting with them.

And that brings us to the golden theme of email marketing – test, test and test again.

You wouldn’t dream of just ploughing ahead with your content or data selections without first applying some testing and results analysis, nor should you jump in with a new strand of subject lines. There are many elements to play with when crafting your compelling subject line. Each of these will have many possibilities, so you should always engage a testing mentality.

If teasers appeal to you, try out different approaches. Should you personalise the subject line? There’s only one way to find out, run some split tests. Do special characters still hold their novelty appeal? Try your message with and without them, which will reveal how they work with your audience. Long, explanatory subject lines always out-perform short sharp ones, or so someone said. Test long versus short, dry against quirky, then you can start to develop your own ideas as to how your customers react to each type.

The Split-test feature in your email marketing platform should play a part in every email campaign that you deploy.