Does it matter when you send your email newsletter? According to a study by email provider Get Response, it does. Evaluating more than 21 million messages sent in 2012, they discovered:

• Almost 40% of all messages are sent between 6 a.m. and noon.
• Subscribers’ top engagement times are 8 a.m. – 10 a.m. and 3 p.m.- 4 p.m.
• 23% of all email opens occur within the first hour after delivery.

Great, now what do you do with the information? Do what we did and run a few tests before you make any permanent changes in your email program. Start by:

1. Randomly divide your list into four equal parts. Then send exactly the same email at four different times. For business-to-business newsletters try, 6 a.m., 10 a.m., 2 p.m. and 4 p.m as a starting point. For consumer products, you might want to consider 6 a.m., noon, 4 p.m. and 8 p.m. as your initial sends.

2. Focus on meaningful measures. If your objective is to just have people read your email, then the open rate is most important metric. For companies using email to inform people and raise brand awareness with no follow-up action required, that’s fine. But most  of the time, you want your readers to do more than just look at the newsletter. Business opportunities occur when people engage with the information by clicking through to a landing page, blog post or ecommerce page.

When we ran the test for our list, we noticed many people would open the email at 10 a.m., but they were less likely likely to take the time to really dive in, click through and read the full article. As with social media, people seem to be looking for a mental break in the mid-afternoon. So when our email showed up around 2 p.m., they seemed willing to learn more.

3. Watch for small differences. While a 1 or 2% variation doesn’t seem like much at first, as your list grows, even small differences start to add up. If your list has 1,000 people, even a 2% shift means 20 more people who see your message. Marketing is a numbers game. The more times you can get people to pay attention to you, the more likely they will eventually buy.

4. Run the test again to test for the day of the week. In their research, Constant Contact  has found Tuesday, Wednesday and Thursday typically see higher open rates than the other days. While this seems fairly intuitive for B2B, we have seen great results for consumer emails on Friday and weekends. Don’t assume that your customers are just like everyone else’s.

We have been sending our email newsletter at 6 a.m. on Wednesday mornings for more than two years. We ran this experiment a few weeks ago, and the results indicated a shift to 2 p.m. would improve our results. We made the change, and have seen significant improvement in both open and click through. We did, however, have one client who sent a note to say he didn’t like the change. It happens, but as Mr. Spock says, “then needs of the many outweigh the needs of the few.”  In our case, the many preferred the afternoon delivery.

Should you make a change in your delivery time? Not unless you test it first.