Subject lines I: Length
Latest posts | Feed | | By Mark Brownlow
Creating a subject line is like creating a work of art.While there are some guidelines a budding artist can follow, there is no "art creation" template that guarantees success. Painting by numbers produces no masterpieces.
So it is with subject lines: there is no simple template to follow to ensure higher responses to your emails. Which is a shame, because what you put in the subject is critical to email marketing success.
What you can do is develop an understanding of the factors that contribute to a winning subject line, and then draw them together to develop "best guess" subjects to try out in practice.
So what are these factors?
Today sees the first of a couple of posts which answer that question. And we begin with perhaps the biggest question: how long should my subject line be?
Subject line length
"Small is beautiful" was always the mantra of subject line length. MailChimp, for example, reviewed a host of campaign stats and found that:
"Shorter subject lines seemed to work better than long subject lines"
...an idea supported by data collected by another ESP, MailerMailer.
But other surveys draw different conclusions.
Emma (also an ESP) checked their own newsletter stats, for example, and discovered:
"...our longer subject line boasted both higher open and clickthrough rates than its shorter counterpart"
Then Alchemy Worx produced data which appeared to show that longer subject lines were outperforming shorter ones.
Most recently, dialog-Mail released an open rate study confirming the idea that shorter is better, but which also suggested that, for example, nine word subjects performed comparably to three-word ones.
So what's going on?
The secret lies in an analysis of the Alchemy Worx report: there is no magic subject line length.
Our desire to simplify led us to seek the ultimate answer to life, the universe and emails: how many characters should the ideal subject line contain (42?)
But subject line length should not be driven by some arbitrary word or character limit.
The effectiveness of the subject line depends on many factors. If you have length as your top priority, you risk compromising on other success factors driving response.
So we might say shorter is generally sweeter. [Not least because many email clients limit the number of characters they will display in the subject line field on the webmail interface, mobile email device or PC.]
But it is still just one factor.
And there will be many occasions when a subject line must be "longer" to contain the words and elements needed to drive a particular response from a particular kind of email to a particular email audience.
Which explains why studies often come up with different results on optimal lengths.
For example, a short headline is often enough to communicate the value of opening a promotional email featuring a single offer.
But informational newsletters might need longer subjects to adequately communicate the value of opening.
So the new length mantra is this:
Use as few characters as you can while still allowing the subject line to do its job
Or put alternatively:
Don't sacrifice on message just for the sake of keeping the subject line short
But what are these other factors, words and elements that impact your subject line length and success? The story continues in Part II...
More on subject lines | Tags: email marketing, subject lines
Permalink | November 05, 2008 | 8 comment(s) - add yours!
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8 Comments:
Mark, we are about to release our latest metrics report. It includes a new chart that shows open rates by individual subject line length for 350 million emails during the first half of 2008. Our data shows a slight bell curve with a good bit of variation in open rates. We also show the results of a test we ran that illustrates how important it is to actually test for your audience's hot buttons. The report will be available to the public Monday, Nov 10 at http://www.mailermailer.com/metrics/.
By 
Raj Khera, on
05 November, 2008
Ah, excellent Raj. I look forward to seeing that.
By , on
05 November, 2008
Mark -
Brilliant post. I spend a tremendous amount of time with my clients discussing the importance of a strong subject line. I've heard Dela's argument (live) at the Email Insider Summit last Spring. Pretty compelling stuff.
It always crack me up. Clients want to know "the best way" to do this or that...the "standard," the "average." What I find time and time again is the answer is simple/complex: IT DEPENDS.
At the end of the day, you have to test. Test. Test. Test. See what works for your customers...for a segment of your customers. Always changes.
dj (Bronto)
By 
DJ Waldow, on
05 November, 2008
Hey DJ. Yep, it's a natural human condition to want clarity and a number to focus on. But like you say, "it depends" is often a much more truthful answer. Even if people don't want to hear it!
By , on
06 November, 2008
Hi Mark
Felt compelled to wade into the "subject Line" argument and I have to say that I find a lot of this research fundamentally flawed. The Alchemy research especially just looks at longer and shorter headlines but did not TEST long versus short in all these cases. I ranted a bit about it in this post that I hope gives some good ideas for subject line research for individual clients...
http://www.nonlineblogging.com/blog/2008/7/3/subject-line-research-a-70-character-pinch-of-salt.html
By David Hughes, on
10 November, 2008
Thanks David,
Yes, all the surveys compare a set of emails with short subjects to a set of emails with long subjects, and then draw conclusions.
The error (I think) is in how we interpret that. We often fall into the trap of assuming that subject lengths were the *only* difference between the emails (as if it was an A/B test), which of course it isn't as you point out.
I like your post: will try and mention it in the rest of the articles.
By , on
10 November, 2008
Thanks for the great post. Really helpful would be knowing the average subject character limit of mail readers. I've read 50, 60, and 100.
By Matthew Cornell, on
04 March, 2009
Hi Matthew,
I don't have an answer offhand, though I'd go for 50 rather than 100 as a number to aim for. But I wonder if knowing an average is helpful.
Say reader A is 20 characters and reader B is 40.
The average is 30. If your subject lines are 30 characters, you're too long for A and not using the space for B.
Plus if all your list is using A, rather than B...
Plus most readers let people adjust the size of the subject line...
...so difficult to come up with a useful average.
Not knowing the possible length displayed is a reason to ensure the "high scoring" words are at the front...then if the end of the subject gets cut off it's not a tragedy...
This approach is discussed in more detail here.
By , on
05 March, 2009
