I just read an interesting report on a study that email service provider MailChimp performed on the effects of list segmentation on email marketing. They compared the results of 10,691 segmented campaigns that 1,998 companies sent to 8,762,207 recipients to non-segmented campaigns sent by the same companies.
You’d expect that the segmented campaigns would produce better results than the non-segmented ones. For the most part, that was true, but there were a few surprises:
