Shorter Subject Lines Rule: MailerMailer

E-mail messages carrying subject lines of 35 characters or fewer significantly outperform those with more than 35 characters, according to a study released yesterday by MailerMailer.

According to the e-mail marketing software-on-demand provider, messages with subject lines of 35 characters or fewer achieved average open and click-through rates of 18.98% and 3.52%, respectively, in the second half of 2008, while those with more than 35 characters achieved average open and click-through rates of 15.38% and 1.75%, respectively.

However, the company warned: “Though, in general, open rates decrease as subject-line length increases, this is not an absolute rule. You should test what your readers respond to.”

According to MailerMailer, its study of more than 300 e-mails found that the top 10 most common words in subject lines are, starting from No. 1 and working down, “news,” “party,” “newsletter,” “free,” “night,” “sale,” “com,” “update,” “holiday” and “week.”

Also according to MailerMailer, average click-through rates for the second half of 2008 were 2.8%, up slightly from 2.73% in the first half.

On the surface, MailerMailer’s reporting on click throughs would seem to contradict a recent study by marketing services provider Epsilon, which reported that average click-through rates were 4.7% in the second quarter of 2008 and 5.9% in the third.

However, Epsilon defines click-through rates as the number of clicks divided b y the number of e-mails delivered. MailerMailer, on the other hand, defines click-through rates as the number of unique clicks divided by the number of opportunities—or links—to click.

So whereas Epsilon would consider 100 e-mails with two links each getting 10 unique clicks a 10% click-through rate, MailerMailer would credit the same campaign with a 5% click-through rate.

According to MailerMailer, religious and spiritual e-mail achieved an average 7.04% click-through rate in the second half of 2008, making it the highest of the sectors MailerMailer tracks. At the same time, restaurant and food-service e-mails saw an average 0.64% click-through rate, making it the lowest of the sectors tracked.

Marketing and advertising e-mails—or e-mails from firms such as ad agencies—didn’t fare much better, achieving an average 1.2% click-through rate in the second half of 2008, according to MailerMailer.

Not surprisingly given the recent housing bust and the economy overall, real estate e-mails saw the biggest drop in click-through rates, from 6.35% in the first half of 2008 to 3.47% in the second half—followed by banking and finance, which saw its average click-through rates fall from 5.74% in the first half of 2008 to 3.68% in the second, according to MailerMailer.

General consumer e-mail—or commercial messages from companies that mail to consumers but are in sectors such as automotive that don’t fit any of MailerMailer’s other categories—saw the biggest gain in click-through rates, climbing from 3.61% in the first half of 2008 to 4.22% in the second, followed by e-mails from consultants, which achieved an average click-through rate of 2.06% in the second half of 2008 compared to 1.46% in the first, according to MailerMailer.

In another finding, MailerMailer determined that Mondays are generally the best days to send e-mail in terms of opens and clicks.