According to a recent MailerMailer analysis that examined almost 1.2 billion emails, email newsletters that had short subject lines (between 4 to 15 characters) had the best open rates in 2013. The same pattern was also seen in an analysis of click rates, which likewise ran the highest for emails with the shortest subject lines. In the study, “open rate” referred to the rate at which the email was actually opened once in the inbox (and presumably read), whereas “click rates” involved the recipient clicking on any embedded links to visit another site once the newsletter or email had been opened.

The MailerMailer study looked at newsletter subject lines from 4 to 15 characters long to over 51 characters long, with a relatively consistent decrease in open rates and click rates the longer the subject line got (the exception to this was between subject lines of 40 to 50 characters and subject lines of 51+ characters, where the 51+ character subject line emails saw as slight increase in open rates and click rates alike). The breakdown of the study was as follows.

  • Emails or newsletters with 4 to 15 characters in the subject line boasted a 16.8 percent open rate and a 2.4 percent click rate.
  • Emails or newsletters with subject lines of 16 to 27 characters had a 13.4 percent open rate and a 2.2 percent click rate.
  • Those emails or newsletters with a subject line of 28 to 39 characters delivered a 12.7 percent open rate and a 2.1 percent click rate.
  • Emails or newsletters headed by subject lines with 40 to 50 characters had a 10.7 percent open rate and a 1.6 percent click rate.
  • Finally, those emails/newsletters with subject lines of 51 characters or more saw a little bump compared to those with 40 to 50 character subject lines: an 11.1 percent open rate and a 1.7 percent click rate.

The data collected in the MailerMailer analysis looked at 62,000 newsletter campaigns and around 1.18 billion sent email messages. All email senders had 25 or more members on their mailing list. Click rate metrics didn’t include those emails that didn’t have any links in them.


MarketingCharts Staff. “Email Open and Click Rates, by Subject Line Length.” Marketing Charts. 10/29/14.