The analysis (pdf), which involved more than one billion emails over nearly 20,000 separate campaigns sent out by several of Epsilon’s US-based clients in the retail and consumer services industries, found that the relationship between subject-line length and open and click rates is not as strong as previously thought.
Overall, shorter subject lines do correlate with higher open rates and click rates for both industries, Epsilon said. However, the rates vary by company.
For example, the open rates for several consumer services clients show a high negative correlation with subject line length, while one client did have a high correlation of subject line length to clicks:
In contrast, for most other companies in the study, Epsilon found the relationship between subject email performance to be relatively weak.
Moreover, Epsilon also analyzed the content of subject lines and found that word order, word choice, and brand and audience awareness are critical success factors as well.
“Marketers should keep in mind that most recipients will likely decide to open an email based on their relationship with the sender and the first 38 to 47 characters of the subject line,” the report stated. “However, that decision may depend less on a subject line of 38 to 47 characters,and more on the information those 38 to 47 characters contain. campaign, the vital piece of information may be the brand name. For another, it may be the consumer benefit.”
Overall, Epsilon recommends that marketers should rethink how they develop subject lines and place increased emphasis on positioning the most important elements first – a concept the company calls “pole position” writing. This includes front loading subject lines with the most important information, keeping the subject line as short as possible to convey the message and using longer subject lines only when there is a compelling reason to do so.
“Companies are spending little time thinking about and testing subject lines, compared with the resources and time devoted to creative development,” said Thane Stallings, senior analytic consultant, Epsilon Strategic Services. “The reality is that more people will see a subject line than its accompanying creative.”