Subject Lines Live – Best of September 2021

With the average office-based worker receiving over 120 emails every day, cutting through the noise has never been harder or more important. 

To that end, here’s our latest analysis of the subject lines which got the highest Click-Through Rate (CTR) for September 2021, from the thousands which run through our platform. 

The daily top 5 can be found here. 

The Top 5 

Subject Line  Click-Through Rate (%) 
MDR Software Update  88.64 
Download the Key Risk Indicators White Paper  83.21 
Your Download – [sender] #[CONTENT/MERGEFIELD1]# Brochure  71.72 
Thank you for your membership application to IHEEM  49.23 
Thank you for attending our webinar  45.52 


MDR Software Update
We’ve been here before! 

Not this specific subject line, but the dominance of a “functional” subject line over more overtly “salesy” messages. 

Our key takeaway remains the same; deliver what your subject line promises, but think about what extra value you could load in. In this case, a comparison of the updated software against its competitors would be relevant and allow you to capitalise on the high number of clicks. 


Download the Key Risk Indicators White Paper
In this case, this exact subject line has made a previous appearance in our top 5. This is a major part of why we do subject line analysis; spotting trends and recuring themes is more useful than commenting on one-off wins.  

We’d all like to think that our audience is on tenterhooks, refreshing our resources page every 12 seconds for the latest bit of thought leadership. In practice though, they just aren’t.  

But they are still interested in your content. So an email when you publish a new resource is a useful nudge. On our own site, we separate our content into Email Marketing, Lead Generation, and Marketing Automation, so we can tailor promotion to which subset a specific reader has previously shown interest in. 


Your Download – [sender] #[CONTENT/MERGEFIELD1]# Brochure 

Delivering resources via email might seem a bit old school, but there are good reasons that we still recommend it.  

First off, you can use these emails to set expectations. This is an email that the reader definitely wants to get, so they will be looking out for it. When you send the resource, use a domain, a sender name, and an email style that is consistent with your other campaigns. If you do this, marketing emails sent to your resource downloaders will be recognised and better received. 


Thank you for your membership application to IHEEM 

In the case of this customer, a membership is the end of the buying journey, so an application definitely deserves celebration! 

Within the body of the email, they point out that processing applications can take several months. This means that acknowledgement of the various stages being completed is important to keep the new almost-member engaged and keen to progress. If you applied to a membership organisation and heard nothing for 3 months, how would you feel? 


Thank you for attending our webinar 

Up until March 2020, webinars were an “engagement stepping-stone”; a way to move leads from passively reading your content to actively engaging with you. Since then, well… 

We’re still some way from knowing how the return of live events is going to play out, so it’s worth taking the time to nurture and engage the people that show up for your webinars. For our own content, this means sharing a PDF of the slide deck with the attendees as well as the recording, to maximise the value they can gain from it. 


The best of the rest 


14.29% of this month’s subject lines contained an element of personalisation, overwhelmingly #Person/First/Name#. This is an identical level to August, and the joint-third highest since we started running this analysis in March 2021 (March and June were first and second respectively). 

What has changed is the difference in average performance; overall, personalised subject lines performed 50% better than non-personalised ones (18.1% CTR vs. 11.6%). This is a much wider gap than we saw in the previous month (28% gap in favour of personalisation). 



Emojis appeared 3 times in all of September’s 105 subject lines, a grand total of 2.86% of entries.  

Marketers who don’t use emojis aren’t missing out, as the highest-scoring of these was in 29th place. When you take the averages, emoji-less subject lines performed 83% better than emoji-including ones (12.7% CTR vs. 6.9%) 


Sender Company Name 

The choice of whether or not to use your company’s name in your email subject lines is a tricky one. Most self-proclaimed “gurus” advocate for personal connections, rather than trying to engage your leads via a business persona.  

However, the 8.57% of subject lines which did include a company name performed 61% better on average than their counterparts (19.4% CTR vs. 11.9%). 


Length (Characters) 

Longer nights, longer subject lines? 

After 4 months in a row of 41 to 50 character subject lines being the most common by at least 9 percentage points, in September the crown is shared between 51 to 60 characters and 100+. Each of these ranges had 18 of the 105 subject lines we analysed this month, between them taking up 34.28% of the places. 

At the opposite end of the spectrum, for the second month running no marketer in the Spotler-verse was pithy and succinct enough to craft a winning subject line in 10 characters or fewer. Strangely, only one subject line appeared in the 91 to 100 character range. 

The longest this month stretches beyond last month’s mammoth effort to reach 236 characters: 

“Dryblower on swimming naked in the iron ore pool; Wall Street keen on exposure to future facing metals: Beament; Strictly Boardroom; Mining struggling to shake ‘dull, dirty, dangerous’ tag; Gold Forum a ghost town as delegates stay away” 



As we said above, when considering #5 of the top five for September, the future of events is not yet clear. A clue may be found in the fact that event-related emails were the second most common of our four types (Sales/Marketing, Newsletters, Events, and Functional) for the first time since June, making up 25% of the list. This is the highest proportion we’ve seen in these stats. 

Our internal position on events is that in-person seminars will return over the course of 2022, and webinars will cede their dominance in favour of a roughly equal split. Thus it does not feel like a radical prediction to expect more buzz around events as we advance through Q4 of 2021 and onwards. 

Go forth and test! 

Trends can come and go, so the need to test is constant. Spotler’s platform makes it easy to analyse your campaign results, and even run split test campaigns if you’re feeling adventurous! Check it out by booking a live demo here. 

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