When is the most effective time of the best day to send your EDM? When are your readers most likely to open and respond? It depends on your industry but several studies indicate Thursday is the best day to send emails. Tuesday is the next best day, closely followed by Wednesday. Weekends tend to fall flat. Several email test results show that the best open rates occur in the afternoon between 2-5pm, with the best time being 3-4pm. The next best open rate occurs between 8-9am. When you send an email, consider testing different times and days and seeing what works best.