Earlier this year, content marketer Linda Formacelli called B.S. on all the e-mail experts who claim there's some special magical window in which your missives to potential customers are guaranteed to get opened at a higher rate.

She's had great success sending pitches at strange hours, such as 11:23 a.m. on a Sunday, Formacelli asserted. While you can't argue with her personal experience about what works for her, new quantitative evidence shows that Formacelli's good results from sending marketing e-mails at any old hour may be a relatively isolated event.

E-mail marketing firm GetResponse recently combed through a whopping 21 million messages to trawl for patterns that can help business owners better time their e-mails. What they found is that there's a definite pattern to when an e-mail is most likely to be opened--but it's not a simple one.

One of the most important conclusions is that sending newsletters during readers' top engagement times of 8 a.m. to 10 a.m. and 3 p.m. to 4 p.m. can increase their average open rates and CTR by 6%.

However, optimizing e-mail timing takes more than awareness of top engagement times. As our research points out, it’s a combination of many factors, including knowledge of time zone differences, your subscribers' daily routines and the practices of other marketers.

GetResponse also found that "e-mails have the best results within the 1st hour after delivery. This is when 23.63% of all e-mails are opened. But 24 hours after delivery, the average open rate is close to zero." So what does this all boil down to?

Timing generally matters as the longer a message sits in someone's in-box the less likely the person is to read it, and the time a message hangs around isn't entirely due to a recipient's lack of interest. In-box clutter also apparently plays a role. "Almost 40% of all messages are sent between 6 a.m. and noon. This can result in in-box clutter, and significantly decrease results for these e-mails." According to GetResponse the takeaways therefore are:

  • If your recipients are occupied with other activities, they won't be able to engage while it’s still fresh, and your message will be crowded out by more recent messages.
  • To optimize the engagement rates for your message, you should schedule it to hit the inbox no later than 1 hour before the top open times, when its chances of getting noticed are the highest.
  • If your e-mailings go to worldwide lists, make sure you use solutions that optimize delivery times in different time zones.

Interested in more information? GetResponse has a whole infographic on the findings that might be helpful.