6 Ways to Write Email Subject Lines that Convert

Let’s be clear – your e-mail subject line can make or break your e-mail campaign success. There are 144.8 billion e-mails sent every day and those e-mails range from critical updates that need to be read to spam-loaded junk trying to dupe you into giving over your cash. Amidst this never-ending wave of electronic envelopes is your message and it has to stand out.

If you want your e-mails to get read, it’s the subject line that’s likely to play the most important part – here are some tips on maximising your subject lines to ensure your message cuts through.

1. Keywords are key

While there are no flat-out, definitive rules that will ensure you maximise your e-mail open rates – even the worst description could work in the right context – there have been numerous studies on words that appeal to e-mail readers more than others. For example, a study by Phrasee, which tested 287 keywords across 2.2 billion e-mails, found that words like ‘sale’ and ‘free delivery’ both had a positive influence on overall open rates. ‘News’ and ‘video’, also showed a positive correlation, but Phrasee notes that it’s largely about surrounding context, the words themselves may not be the trigger.

Research by Yesware came to a similar conclusion though they found that words like ‘campaign’ and ‘steps’ lead to higher open rates for their purposes. Campaign Monitor studied more than 360,000 e-mail campaigns and found that ‘invitation’, ‘introducing’, ‘we’, and ‘new’ were among the top performing words in regards to influence on open rates. The appearance of ‘we’, in particular, highlights the importance of personalisation – ‘you/your’ also factored high in their research.

Cumulatively, what the research suggests is that personalisation, time-sensitivity and highlighting special offers can play a big part in maximising open rates. Equally important, however, is avoiding those words that don’t work – some of those can truly kill off your campaign before you’ve even begun.

2. Avoid words that don’t work

Looking across the same studies, there are numerous words that have a definitive effect in lowering open rates. In a study conducted by MailChimp, they found that while the word ‘free’ should be avoided (as it can trigger some spam filters), three other words were found to have a negative impact – those words were ‘help’, ‘percent off’ and ‘reminder’. Yesware found ‘calendar’, ‘online’ and ‘interested’ reduced open rates while Phrasee highlighted ‘report’, ‘webinar’ and ‘monthly’ as poor performers. There’s not a definitive common theme among these, but it does suggest that people are more attuned to advertising jargon, and they’re actively tuning out traditional marketing messaging.

3. Avoid repetitive subject lines

If you’re sending the same campaign e-mail over and over again, you’re open rates are going to progressively decline unless you get creative with your subject lines. How big of a decline can you expect? As part of MailChimp’s study, which analysed the open rates of over 200 million e-mails, they sent out the same invite several times to measure the progressive impact. In the first send out, the open rate was 8%, for the second, 6.3%, then 5.1% on the third and 3.5% on the fourth. They altered the subject line slightly, but the main message was the same in each.

Repeating the same message over and over is not an effective tactic – if you want to remind people of your offer, best to think of new ways to frame it in order to maximise your outreach opportunities.

4. Unnecessary punctuation

Calm down with the punctuation in your subject line. The best subject lines are short, to the point and provide the reader with an incentive to open your e-mail and explore your message further – cluttering up that one sentence you have with unnecessary punctuation can severely damage your open rates.

What kind of unnecessary punctuation, you ask? In particular, unnecessary commas, colons or, the worst, exclamation points. Campaign Monitor’s research found that subject lines that end with an exclamation mark tend to result in more opens than those that don’t, so the exclamation point can be used to good effect, but don’t be putting down seven of those things in a row. You’ll be heading straight to the junk folder before they’ve even read the whole sentence.

5. Subject line length

You don’t have time to waste with your subject lines, so concise and to-the-point is the best way to go. The traditional e-mail marketing rule-of-thumb is 50 characters or few, which is backed up by research from MailChimp, though they do note that in campaigns where subscribers were highly targeted, readers seem to appreciate additional info in the subject line.

Research by ShowMeLeads, based on analysis of 260 million e-mails from 540 campaigns, found that marketing e-mail subject lines with 6-10 words had a 21% open rate. Subject lines with 5 or fewer words were opened 16% of the time, and those with 11-15 words in the subject had a 14% open rate. With more than 52% of the subject lines studied falling into this last category. It’s clear from these numbers that 6-10 words is the sweet spot, and should be what you’re aiming for in your subject line copy.

Source: Yesware
Source: Yesware

6. Personalisation is key

Overall, the key point that comes up in the data is that personalisation is the most effective tactic. Personalization is a great way to get attention, and thus, increase open rates, but Phrasee cautions that:

The main thing about personalisation is to ensure you don’t deliver a disjointed user experience. If the subject line is personalised, but the email content isn’t, guess what? You may gain opens, but have done nothing to drive clicks. It leaves users with a negative experience.

Campaign Monitor’s research found that including the recipient’s name increased open rates more than any other word, underlining the value of personalization, while MailChimp found that localisation – including the recipient’s home city name – influenced greater open rates than including the person’s name.

However you look at it, personalisation is powerful, and, used correctly, will have a positive impact on your overall open rates. As a result, your business can make more money.

So there you are, six data-backed notes on e-mail subject lines to help you increase the effectiveness of your next e-mail marketing campaign. Researching best practices is the key to constructing a truly effective campaign, and paying attention to every detail – from the subject line and the e-mail copy to the landing page – every element counts towards the final result.