We ran a recent e-mail marketing campaign and despite the research that mentioned that B2C e-mails should be sent out preferably on Friday through Sunday.  We ran a comparison test and found just about the opposite effect.   We staggered a e-mail campaign to send out over multiple days. The majority of the list comprised of B2C leads and prospects.  What we noticed was that the exact opposite was true.  B2C had a higher, click and open rate for the mid-week emails.  All emails had exactly the same content. The only difference in this test was the time and day of the week.