With Boomerang, you can write an email now and schedule it to be sent automatically at the perfect time. Just write the message as you normally would, then click the Send Later button. Use our handy calendar picker or our text box that understands language like "next Monday" to tell Boomerang when to send your message. We'll take it from there.
First Download the Software Boomerang
Then, go to Compose mail and then to the option ( Save now and then to Send Later) and you can choose the duration at what time you want to send mail.
And now , your Message can be sent.
Incase , If you want to reschedule or make any changes you can Click on Boomerang and do the rescheduling.