Email Subject Lines Testing: Why And How You Should Be Doing It

It is important to split test your business’ email subject lines so that you understand and constantly improve your email marketing strategy. Split testing, or subject line testing, or A/B testing, can significantly increase your open rates, click through rates, and conversion rates. Tested and proven subject lines for your emails will help you up your email marketing game.

Why Email Subject Lines Are Crucial

As an email marketer, you must be aware of how vital it is to develop email subject lines that entice and draw in your audience. It is estimated that the average person receives about a hundred marketing emails in a day, and around one-third of people choose to open an email and read it solely based on the subject line of the email.

So, you see, there’s a lot depending upon your email subject lines. After all, what’s the point of sending out great email campaigns to your audience when your emails aren’t even being opened by them!

This is why you have to stop relying on intuition, and start relying on hard cold data. To get this data, you will need to test out different subject lines for your emails, measure different metric, and see what’s working for you.

In this post, we are going to be talking about the different steps involved in email subject lines testing.

A Guide To Email Subject Lines Testing

In order to successfully test out different subject lines for your emails, you need to have a systematic approach. This guide will help you take a step by step approach to email subject lines testing.

Step 1: Select a Segment of Your List

It’s never a good idea to blindly send out the same email to your whole email list. This is why list segmentation is so important. List segmentation allows you to divide your email list into smaller sub-lists, so that you can plan out target email marketing for each segment.

Now one type of email or one type of subject line may not resonate well with your whole list. However, each segment of your email list will have certain traits or characteristics that you can study so that you are able to understand them more deeply.

Send segmented list email campaigns

Take some time to think about what aspect of your email marketing campaign will resonate well with that particular segment, and craft your subject line accordingly. If you already have segmented your list, this step will be easy, but if you haven’t yet done it, you can check out our post on list segmentation that will help you.

Step 2: Test Out One Aspect At a Time

There are different aspects to subject line testing, and it can become overwhelming sometimes. Try not to test out multiple different aspects at the same time. Test out only one aspect so that you can easily measure the results and plan your next move accordingly.

Some of the most commonly tested aspects of email subject lines are:

1) Particular words in the subject line

It is interesting to see that even a single word added/ removed/ changed in the email subject line can significantly alter the way your subscribers respond to your emails.

For example, it has been observed that a single word such as ‘ebook’, or ‘pdf’ instantly increases the open rates of emails. This could be probably because the single word tells your subscribers there is something informative and useful that they can download if they open your email.

It is worth the effort to test out different words like these to see which works and which doesn’t.

2) The length of your subject line

It is quite obvious that the length of the subject line determines your open rates to a large extent. The shorter your subject lines, the better.

However, each target audience is different, and sometimes even each segment of your list will respond differently than the rest.

It pays to A/B test your subject lines to see what works well with your audience. This way you will understand what your audience really expects from you and your email campaigns.

3) Personalisation in your subject lines

A personalised subject line always shows your customers that you care. Now, this doesn’t mean that you go overboard with personalising your emails and add their names very frequently in the subject and body of your emails - that’s surely a turn off.

Personalise email subject lines

Personalisation of your emails could be as simple as adding the word ‘you’ in the subject line of the email. For instance, “The Top 10 SEO Techniques You Need To Know in 2019”. This may earn you a higher open rate when compared to the subject line “Top 10 SEO Techniques in 2019”.

However, as your audience is evolving along with you, it is important to keep testing out different subject lines at regular intervals. What worked in the past may not work today.

4) The type of text in the subject line

Small tweaks in the way your subject lines look can also change the way your audience reacts to it. Play around with caps, punctuation, letter spacing, and even emoticons to see how your audience receives it.

Although, you must be careful as there’s a fine line between fancy looking subject lines and spammy ones.

Step 3: Use a Portion of Your List For A/B Testing

If you have a sizeable email list, it can be beneficial to test out different email subject lines for different sections or segments of your list. This way, you can only send out your tester emails to small segments of your list, and see which one works better.

Once you’ve determined which of your subject lines is better received by your list segments (which ones have the more open rates), you can then send out your emails with those subject lines to the larger portion of your list.

If you have a small list, though, you will not be able to get any accurate results if you only test out a couple of email addresses on your list, so it makes more sense to carry out a general A/B test on your whole list so that you can use the results to shape future subject lines.

However, if your list is quite big, it would be wiser to only test out a small portion, otherwise you would be sending your weaker subject line email to half of your email list.

Step 4: Analyse The Data

Once you have split tested your email subject lines, it's time to gather all the data and study it carefully. Be careful to always keep your final goals in mind when you do this, so that you can fulfill the purpose of your email campaigns.

Although your open rates and click-through rates are of utmost importance, there’s one more metric that needs to be held higher - your conversion rates.

Analyse the date captured from email subject lines testing

Even if one type of subject line leads to more open rates and click-through rates, what ultimately matters is your conversion rates.

Carry Out Regular A/B testing For Best Results

Email subject lines testing is not a one-time affair. In order to stay ahead of your competition, you need to consistently test out different types of subject lines. Your audience is constantly changing, and you have to keep an eye on the trends.

Analyse different metrics and see what’s best for your business in terms of results. Yoru resus might show that one of your email subject lines was opened much more than another, but then the other types of subject line may have been more appealing to your target audience, or a specific segment of your audience.

There’s no hard and fast rule that one type of subject lien is the best, and there’s always room for improvement, so keep trying out different combinations and tactics.

Keep testing out different subject lines

As you keep testing out different subject lines, you may also be discovering new things you may not have noticed about your email list before. Maybe your audience prefers shorter subject lines, or maybe personalisation does not really matter to them. Maybe emoticons don’t really resonate with your audience, or maybe they relate better to a subject line that tells them exactly what’s inside your emails.

You will never know these things unless you dedicate some time and energy to test out different types of subject lines with your email list. It could also be that a style of writing subject lines is becoming too popular and common, and so your audience has started to ignore it.

The more you take the time to study your audience and see what they like, the more that will reflect in your emails, and the more your audience will respond to you. Customers stay loyal to companies who actually care about them without just wanting to sell them stuff, so make sure your emails are well balanced with valuable information and sales emails.

There is no shortcut to great email subject lines. Everything takes hard work, patience, and a whole lot of testing out. This is something that you cannot plainly rely on your instincts for.

So, go out and test those subject lines! :)