A recent eROI study which examined open and click rates of mailing lists of all sizes across all the days of the week found, on average, Sunday was the best day with an open rate of 30.8 percent and a click rate of 7.2 percent. Before all marketers rush out and clog up everyone’s lazy Sunday afternoon with e-trash, the study also indicated that the best day to mail varies with list size. The bigger the list, the less efficient. Lists over 200,000 do well on Saturday. Micro mailers (extremely small) do best on weekends. Small mailers do best on Friday. Mid-sized lists do best on Monday and Friday.
