It might come as a surprise, but according to a new study by U.K.-based e-mail service provider Pure360, the best time to send a commerical email is outside of office hours.

In a study of 660,000 messages sent by 34 companies, Pure360 reports that just 9% of e-mails were opened between noon and 2 p.m., and 62% of those messages were news or magazine alerts.

However, according to Pure360, almost half, or 48%, of marketing e-mails in the study were opened outside office hours.

When I think about my email habits this actually makes sense.  If I receive a commercial email during office hours that is not from a client, friend, or prospect I immediately delete it.  However, if I receive a commercial email and it sparks my interests outside of office hours, I’m much more likely to explore a little deeper.

You could actually test this theory yourself with PURLs.  Send a campaign during office hours and track the response rates in real time.  And then do the same thing during office hours.  Doing this one thing could drastically increase your email marketing response rates.