Should you want to send an email in Outlook in the future at a specific time, do the following:
1 – Create a new message.
2 – Click on the Options tab.
3 – Click on the Delay Delivery button.
4 – Check the Do not deliver before box, and specify the date and time you wish the email to be sent.
Your email will stay in your Outbox until the designated time.
Unfortunately, this tip is available only for Windows Outlook.