1. Go to any Lead/Contact/Account Scroll down to Activity History.
2. User will find Schedule One-off Email button.
3. Click on the Schedule One-off Email button, user will be navigated to the Schedule One-off Email tab.
4. Email of Lead/Contact/Account will be auto populated and User can choose required BCC Email,Template Folder and Required Template.
5. So User have two options either Send now or Schedule for later send.
6. Select Send Now for sending the email immediately and Schedule for Later send
will give you the option to schedule for sending the email in future.