The best days to send a marketing or sales email to your contacts has been proven to be Tuesday and Wednesday.
Tuesday / Wednesday = Increased Response
Studies conducted by online research analysts have shown that the best days to perform a mail-out to your e-commerce customer list are Tuesday and Wednesday, as this is when people are more receptive to communication. This means that they are more likely to read your content and click on links, meaning more sales.
On Mondays, everyone is still recovering from a hectic weekend. On Thursday and Friday, people are already too busy looking forward to the weekend. We've actually experimented with this, and received the best results by sending out emails at around 2-3pm on a Wednesday.