Sending your email at even ten minutes later than normal can change your open rates. The only benchmark to use for your success lies in your previous email campaigns. So how do you know? Process of elimination.
Examine subject lines: Look for the highest open rates and read the subject lines for those open rates. Narrow it down to the top three and see how other subject lines measure up to those. Were the successful ones particularly clear or clever? Identify the weakest subject lines and look at their open rates. This will help you identify how important your subject line is. Chances are it is fairly important.
Time of day: If you are inconsistent with your send dates and times, try to identify two or three that are close together (same day, same portion of the day). Now identify a campaign that is furthest from that time of day and day of the week. For example, compare a Tuesday morning with a Saturday night. Which is more successful? Start whittling down your list of send times and days by inching closest to your most successful. You’ll likely identify one to three peak times to send.
Other factors: Keep in mind that people are less likely to act on holidays and more likely to act on the days leading up to holidays – if your email is commercially driven. Consider hectic times of the year and the conveyed importance and relevance of your email. Finally, make sure that you keep your sender’s name consistent with your business name.
Put it all together: Look at all the high-success open rates and see what they have in common in terms of sending time frames and subject lines, keeping in mind the other factors we mentioned. This will help you identify why people aren’t opening some weeks and why your open rates jump on other weeks. No matter what you discover, remember that when dealing with the behavior of people there is always a little bit of random thrown into the equation.