A new report by Yes Lifecycle Marketing delves into this very topic, highlighting how various types of subject line components can impact marketing in different industries. 

Here’s a bit of insight into the research, along with a few examples of brands displaying best practice.


Most tend to agree that personalisation is an effective marketing tool. Econsultancy’s Email Census found that marketers who are proficient in personalisation are more than twice as likely to rate their overall email campaign performance as ‘excellent’ or ‘good’ than marketers who are not.

The research by Yes Lifecycle Marketing backs this up with further proof of success. It found that emails which included personalisation in their subject lines significantly outperformed those that didn’t, with these emails generating 50% higher open rates, 58% higher click-to-open rates, and double the unique click rates.

These results stem from the analysis of more than 7bn emails sent in Q2 2017, but surprisingly, the report also states that just 2% of all these emails included personalisation in their subject line.

As well as shunning personalisation altogether, it also appears as if most marketers are focusing on its most simplistic (and less effective) forms. Many brands merely use the recipient’s name rather than any personal data or information generated from interaction or engagement, including factors like abandoned baskets or previous purchases.

This subject line from Mr. Porter is a rather poor example of personalisation, merely hinting at the promise that it’s customised for me, when in reality it’s generic.

In contrast, a brand that often draws on deeper levels of personalisation for its subject lines is Trainline. The below is an email I received after looking up train times from London to Exeter. 

Incorporating my name, previous browsing behaviour, and the incentive of a cheaper ticket – it’s a good example of data-driven targeting.


According to research from Return Path, over half of all emails are now opened on mobile devices. This is pertinent particularly when it comes to the length of subject lines, as the average number of characters displayed on mobile is 35 – anything more is cut off and replaced by an ellipsis. 

Yes Lifecycle Marketing found shorter subject lines to be the most effective, generating an open rate of 18.5% compared to 14.8% for long subject lines, and 13.8% for mid-length subject lines. 

Of course, it is important to remember that other factors might have affected this, including things like type of industry and pre-header text.

One aspect that I find particularly interesting is that subject lines over 60 characters generated higher open rates than those between 21 to 60 – even when the end might have been cut off. This is perhaps due to natural curiosity, with users feeling inclined to find out how the sentence finishes, coupled with a long subject line evoking the sense that a brand has lots of offer.

In terms of industry, retail appears to benefit the most from short subject lines, seeing an 18.3% open rate on this compared to 15.3% for longer subject lines. The fact that this varies across industries does suggest there is no set formula, but a short and snappy message coupled with a specific offer appears to be a winning combination for retailers.

This subject line from H&M is rather in-your-face, but it’s also a good example of how to use urgency to drive click-throughs.

Types of trigger

Another important factor to consider in conjunction with subject line length is the type of triggered campaign. In other words, whether or not it’s an email for a customer that has abandoned their basket, signed up to a newsletter, or failed to engage with a brand for a significant period of time.

In Q2 2017, Yes Lifecycle Marketing found 69% of brands sent welcome emails with subject lines between 21 to 50 characters long. This length generated an open rate of 24.3%.

In contrast, just 7% of brands sent welcome emails with subject lines between one and 20 characters. However, this length achieved a 32.4% open rate, showing that short welcome emails are effective at engaging users.

Despite heading into mid-range territory in terms of length, this subject line from Oliver Bonas uses an abbreviation to help keep it as short as possible, while the discount drives interest.

Short subject lines have also been found to successfully increase open rate for abandonment emails. This is because most longer subject lines include incentives to complete a purchase, which can be scanned without opening the email, whereas short versions can evoke intrigue.

Across all triggers, including birthdays, welcome or abandonment, subject lines that include a specific offer in the subject line drive the most opens. 

What about emojis?

While we’ve established that the shorter the better, brands are also experimenting with other strategies including emojis and slang.

It can be divisive tactic, but Get Response suggest that emojis can be a good thing. It found that emails with emojis in the subject line had a slightly higher open rate of 26.67% versus 24.07% for those without. 

Similarly, Return Path found that emojis relating to seasonal events increased open rates. Valentine’s Day-related emails using the ‘lips’ emoji generated an open rate of 24%, compared with 20% for the same email with a text-only subject line. 

Stationery brand Papier often does a similar thing, injecting a bit of flair and character into its subject lines with themed emojis.

Another benefit of using emojis is that they save space, especially on mobile. Instead of writing a super-long subject line, an emoji can be used in place of a word, conveying a lot of information in just a single character.

Elsewhere, it can also be effective for connecting with a target audience, particularly younger consumers who typically use emojis in every day communication. 

In conclusion…

Most research suggests that short, personalised, and offer-based subject lines are the most effective – as long as it’s in a style that reflects the brand’s wider tone of voice.

That being said, with so many variable factors, testing is the only real way for brands to define the kind of subject line that will truly resonate with their audience. 

To learn more about email marketing, check out Econsultancy’s range of training courses.