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No Optimal Subject-Line Length: Study

By Ken Magill
Please, oh please let Return Path have the last word on subject-line length
One of the more irritating debates in email marketing over the years has been the one over optimal subject-line length.
Of course there are space constraints. And of course they should be taken into account.
But the idea that there is a magical number of characters that by their number alone will drive or suppress action is just plain silly.
The subject-line-length debate has been covered here repeatedly. Hey, just because I think something is stupid doesn’t mean I consider myself above capitalizing on it.
As most Magill Report readers are no doubt aware, there isn’t a whole lot I consider myself above.
Email intelligence and security firm Return Path recently weighed into the debate with a white paper. [Full disclosure: I have written white papers for Return Path, but not this one.]
“Overall, our research indicates that there is actually no correlation between the length of a subject line and its read rate” the white paper said. “When comparing the number of characters in a subject line to the read rate, the Pearson’s correlation value [a measure of whether there is a correlation between two data points] was -.03, which shows us that there’s no relationship between the number of characters in a subject line and whether or not the email is opened.”
The white paper’s author also made the following commonsense observation:
“Just because there’s no specific correlation between length and read rate doesn’t mean you can fully ignore how many characters are in your subject line. Different devices have different display capabilities, so it’s important to keep this in mind as you write your subject lines.
“A typical desktop inbox displays about 60 characters of an email’s subject line, while mobile devices show just 25-30 characters. If your audience is primarily reading your emails on smartphones, place the offer or call to action at the beginning of the subject line where it’s more likely to be seen.”
Beyond taking subject line character constraints into account, counting characters is a waste of time. It’s what’s in the subject lines that matters.
The Return Path study found that “urgency” subject lines—those with words such as “expire,” “running out,” “limited time,” and “hurry” in them—performed best, followed by “benefit” subject lines—with words such as “best, “cheapest,” and “easiest”—and “command” subject lines—with words such as “add,” “click,” and “download.”
Tell them what you want them to do. Give them a benefit. Give them a deadline. These are direct-marketing tenets established long before email came along as a commercial channel.
The channel may change. Basic selling tenets do not.
Access Return Path’s study here.

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