You want to send an email at a later time, but you’re going to be busy then.
What you can do is schedule sending an email at a given time and date. Most email programs allow you to do this, even on your cell phone. Here’s how with the main programs (other programs will be similar).
Gmail: When you go to hit send, click the small down arrow. A menu for delaying that email will open. Choose one of the suggested times or set your own.
Outlook: Look for the Tag Menu on the email message ribbon and click the small down arrow in the right-hand corner. The menu allows you to schedule the email send.
Mac Mail: Click the pop-up menu next to the Send button, then choose an option. Emails you choose to send later appear in the Send Later mailbox in the sidebar.
Android phone or tablet: After composing your Gmail, tap More at the top right, tap Schedule.
Iphone: Tap and hold the Send button to see your scheduling options. You can see scheduled emails in the Send Later mailbox.
You can also delay sending all emails by creating a Rule to defer delivery by x number of minutes. It has several steps, so Google “email schedule rules”.