When it comes to e-mail subject lines, shorter is sweeter to the consumer.
A study of subject line effectiveness released last week by Epsilon showed that while shorter subject lines do generally perform better than longer ones, the relationship between subject line length and response is weaker than previously thought.
The research showed that, overall, shorter subject lines correlate with higher open rates and click rates for both industries.
Epsilon evaluated the correlation between the length of a subject line of each campaign and the unique open and total click rates. In addition to subject line length, the study suggests that subject line word order, word choice, and brand and audience awareness are also critical success factors.
For e-mail subject lines, the Epsilon study suggests the following rules of thumb:
1) Front load subject lines with the most important information
2) Keep the subject line as short as possible to convey the message
3) Use longer subject lines only when there is a compelling reason to do so
4) When in doubt, test
For the study, five Epsilon clients were chosen at random from Epsilon’s retail client base. The analysis includes all messages from these clients between June 2007 and June 2008, with the exception of messages sent to fewer than 100 individuals and messages with a personalized subject line.
Epsilon analyzed the impact of the more than one billion e-mails over nearly 20,000 separate campaigns sent out by a selection of U.S.-based clients in the retail and consumer services industries.