Emails are not to be sent at any time. Most marketers have discovered that at certain times emails do better than other times.
Before smashing the send button or scheduling your email automation, remember to check the time of the day and the day of the week.
Perhaps those are the most important aspects as far as timing is concerned. According to research the best time to send your email marketing template is around 10 AM.
At this time, most emails are opened and that places your email in a better position of being opened. Never send emails at 3 AM and 4 AM, that will be really weird to the receiver.
When it comes to the best day for sending emails, research has shown that Tuesdays and Thursdays are the best. So, work within those days.