Study Questions Monday as Best E-Mail Day

A new study by e-mail service provider ExactTarget contradicts recent reports stating that open and click rates are best for e-mail messages sent out on Mondays.

The Indianapolis company reported “serious inconsistencies” between the best day for opens and the best days for clicks.

A report based on the study that was released Feb. 22 said that two studies were released last year touting Monday as the best day to send e-mail.

The first, published by Return Path, found that deliverability rates were best for messages sent on Mondays. Also, eROI conducted a study published by MarketingSherpa that suggested open and click rates are best on Mondays. Both studies challenged prior thinking that Tuesday was the best day for marketers to send e-mail.

ExactTarget's study analyzed data from December 2003 to November 2004 representing 2,000 organizations, 160,000 e-mail campaigns and 800 million messages. Findings include:

· Most marketers send e-mail midweek. More than 97 percent of e-mail campaigns are sent Monday through Friday, leaving the weekends open for marketers who send campaigns during the weekend.

· The best days for opens may not be best for clicks. Month-by-month results show significant inconsistencies between the two. Marketers must decide which they want to drive. Maximizing open rates is important for brand exposure while clicks are key for conversions.

· Monday's ranking falls. MarketingSherpa published its results in late July, stating the best day to send was Monday. This study was based on results for second-quarter 2004. ExactTarget's analysis for second-quarter 2004 also suggests that Monday was the best day to send in that quarter. However, since that report was published, Monday consistently has ranked fifth and sixth for “best day to send” in terms of open rate.

· Wednesday to Friday delivery maximizes open rates. Starting in July, the best days to maximize open rates shifted to later in the week. For July to November, Friday performed best, but was less than one-half percent ahead of Wednesday and Thursday in average open.

· Weekends rule for generating clicks. Weekend results are mixed, with open rates below average. But Sunday and Saturday yield the highest click-through rates, respectively. With less competition for the inbox on weekends, people who open e-mail have more time to read and respond to it.

· Results by industry vary. High-tech companies fare well on Fridays, membership organizations on Wednesdays and online retailers drive twice the click-through rates when sending on Sundays.

· Inbox competition is alive and well. Sending at peak times increases competition for attention in the subscriber's inbox. Open and click-through rates are generally lower when more people are sending. In the business services industry, campaigns are mainly sent on Mondays (nearly one-third of all campaigns for this industry), but Monday open rates are 8 percent lower than the industry average.

“The results of the ExactTarget study indicate that marketers need to rethink the best times for sending e-mail,” said Morgan Stewart, director of strategic services for ExactTarget and the author of the report. “There is no simple answer to which day is best for sending e-mail that applies across the board. The results vary each month, by industry and by target audience. The notion of a universal 'best day to send e-mail' is a moving target at best, and a myth at worst.”

Instead of following industry trends, Stewart said, “marketers should test the results for different days [that] may be appealing to their target audiences.” ExactTarget's report offered steps on how to conduct a basic “Best Day of the Week” test:

1. Create a single e-mail message that is not date or time sensitive. The message should be exactly the same so that other variables, such as subject line or content, do not affect results.

2. Randomly assign customers to equal-size test groups. (If you test using your entire customer list, determining sample sizes is unnecessary.)

3. Select a time of day that messages will be sent each day and keep it the same for each day you test.

4. Capture results by recording the open and click-through rates for the campaigns at equal intervals past each send. The report suggested waiting about 72 hours for responses. (If you test Monday and Tuesday, record Monday's results on Thursday and Tuesday's results on Friday.)

5. Compare results. To determine whether the results are significant or the result of random chance, use a significance calculator to compare campaign results.

Melissa Campanelli covers postal news, CRM and database marketing for DM News and To keep up with the latest developments in these areas, subscribe to our daily and weekly e-mail newsletters by visiting

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