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Want To Boost Open and Click-Through Rates? Use Shorter Subject Lines and Increased Links, EmailLabs Analysis Shows

REDWOOD CITY, Calif. (Oct. 4, 2004) – Email marketers seeking to increase their open and click-through rates would be wise to keep subject lines short and hyperlinks plentiful, according to a new study from EmailLabs, the leading Web services provider in the email marketing space.
The company today announced the release of an analysis of key variables involved in the delivery of permission emails from more than 650 companies during the first quarter of 2004.  The EmailLabs study compared and tested message size, the number of embedded links and the length of the subject line. (See chart below.)

The findings: subject lines shorter than 50 characters in length, as well as an increased number of hyperlinks, led to increased open and click-through rates.  Message size did not appear to be a significant factor in boosting rates, although messages in the 20 to 79 kilobyte (KB) size range had slightly higher open and click-through rates than messages from 3 to 19 KB.

 Subject line lengths were divided into zero to 49 characters and 50+ characters.  When analyzed, the zero to 49 character subject lines had an open-rate 12.5 percent higher than the 50+ character subject lines. Click-through rates for the zero to 49 character group were 75 percent higher than the 50+ group.
The differences in open and click-through rates were smaller but still distinct when evaluating the number of hyperlinks contained in the email.  Emails with 25 or more links had an open rate of 12 percent higher than those containing fewer than 25 links, and a click-through rate of 29 percent higher than for emails with fewer than 25 links.

 “These results support some long-held beliefs among email marketers,” said Loren McDonald, VP of Marketing, EmailLabs.  “In general, email marketers should limit the length of their subject lines to less than 50 characters, and should include as many hyperlinks as possible.  In addition to a shorter subject line being visible in its entirety in most email clients, recipients comprehend shorter subject lines more easily and quickly.

“The more links there are, the greater the chances that one or more will resonate with the recipient and motivate them to click through,” McDonald said.  “While 25 links may sound like a lot, navigation and administrative-type links in best practices newsletters can easily reach 15-20 links by themselves.”

For message size, 43 percent of client messages sent were in the 20 to 79 KB range, followed by 28.4 percent for 10 to 19 KB, 25.9 percent for three-nine KB, 1.4 percent for less than three KB and one percent for 80 KB or larger. Messages in the 20 to 79 KB size range had open rates and click-through rates of 4 percent and 8 percent higher than messages in the three-to-nine KB range. Interestingly, although only 1.4 percent of messages sent were less than 3 KB, those messages had the highest average open rate, bounce rate and unsubscribe rate.

“Marketers shouldn’t be too concerned with the size of their messages, with our analysis not revealing any negative affect on performance from larger-sized messages,” McDonald noted.  “That being said, the general rule of thumb to try to limit messages to 40 to 50 KB is not a bad idea, due to size limits on the receiving end.

“While we believe these findings are compelling, it is essential that email marketers conduct split tests across key variables to determine what works best for their specific customers and subscribers,” McDonald advised.

The EmailLabs analysis was based on the results of 23,475 email campaigns sent by more than 650 companies between January 1 and March 31, 2004.

Affect of Message Sixe, Subject Line Length & Number of Links on Email Results

About Uptilt
Uptilt is a leading provider of Web-based CRM solutions to more than 350 Global 2,000 and middle market companies. The company currently offers two solutions: advanced email marketing automation through EmailLabs and sales force automation through SalesCenter. Headquartered in Menlo Park, Calif., Uptilt was founded in 1999 and is privately held. For more information, visit, and

Loren McDonald
925.202.5976 cell

Mandy Mladenoff
SHIFT Communications


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Last Updated: May 15th, 2006 - 16:32:55