Open Outlook and start a new email
Go to the Options tab
Select Delay Delivery
Check Do not deliver before
Choose the date and time you want the email sent
Close the dialog box
Click Send
Keep Outlook open until the email is sent if required by your account settings
To delay all outgoing emails, go to File
Select Manage Rules & Alerts
Click New Rule
Choose Apply rule on messages I send
Select defer delivery by a number of minutes
Set the delay time
Finish and save the rule