I tend to find the best days to launch a new product is on a weekday (preferably Tuesday and Wednesday). Monday, Thursday and Friday are too close to the weekend and people tend to focus on the weekend more on those days.

It's human nature for people to not be in the mood for receiving emails about new product launches on weekends. It's not how most people want to spend their free time. Product launches will get more attention the closer it is to the middle of the week.